js: Convert _.map(a, …) to a.map(…).

And convert the corresponding function expressions to arrow style
while we’re here.

import * as babelParser from "recast/parsers/babel";
import * as recast from "recast";
import * as tsParser from "recast/parsers/typescript";
import { builders as b, namedTypes as n } from "ast-types";
import K from "ast-types/gen/kinds";
import fs from "fs";
import path from "path";
import process from "process";

const checkExpression = (node: n.Node): node is K.ExpressionKind =>
  n.Expression.check(node);

for (const file of process.argv.slice(2)) {
  console.log("Parsing", file);
  const ast = recast.parse(fs.readFileSync(file, { encoding: "utf8" }), {
    parser: path.extname(file) === ".ts" ? tsParser : babelParser,
  });
  let changed = false;

  recast.visit(ast, {
    visitCallExpression(path) {
      const { callee, arguments: args } = path.node;
      if (
        n.MemberExpression.check(callee) &&
        !callee.computed &&
        n.Identifier.check(callee.object) &&
        callee.object.name === "_" &&
        n.Identifier.check(callee.property) &&
        callee.property.name === "map" &&
        args.length === 2 &&
        checkExpression(args[0]) &&
        checkExpression(args[1])
      ) {
        const [arr, fn] = args;
        path.replace(
          b.callExpression(b.memberExpression(arr, b.identifier("map")), [
            n.FunctionExpression.check(fn) ||
            n.ArrowFunctionExpression.check(fn)
              ? b.arrowFunctionExpression(
                  fn.params,
                  n.BlockStatement.check(fn.body) &&
                    fn.body.body.length === 1 &&
                    n.ReturnStatement.check(fn.body.body[0])
                    ? fn.body.body[0].argument || b.identifier("undefined")
                    : fn.body
                )
              : fn,
          ])
        );
        changed = true;
      }
      this.traverse(path);
    },
  });

  if (changed) {
    console.log("Writing", file);
    fs.writeFileSync(file, recast.print(ast).code, { encoding: "utf8" });
  }
}

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

frontend_tests/node_tests/filter.js

@@ -35,7 +35,7 @@ people.add(steve);
 people.initialize_current_user(me.user_id);
 
 function assert_same_operators(result, terms) {
-    terms = _.map(terms, function (term) {
+    terms = terms.map(term => {
         // If negated flag is undefined, we explicitly
         // set it to false.
         let negated = term.negated;
@@ -508,9 +508,10 @@ run_test('canonicalizations', () => {
 });
 
 function get_predicate(operators) {
-    operators = _.map(operators, function (op) {
+    operators = operators.map(op => ({
-        return {operator: op[0], operand: op[1]};
+        operator: op[0],
-    });
+        operand: op[1],
+    }));
     return new Filter(operators).predicate();
 }
 

frontend_tests/node_tests/list_render.js

@@ -268,7 +268,7 @@ run_test('sorting', () => {
     };
 
     function html_for(people) {
-        return _.map(people, opts.modifier).join('');
+        return people.map(opts.modifier).join('');
     }
 
     list_render.create(container, list, opts);

frontend_tests/node_tests/message_fetch.js

@@ -132,9 +132,9 @@ function config_process_results(messages) {
 }
 
 function message_range(start, end) {
-    return _.map(_.range(start, end), function (idx) {
+    return _.range(start, end).map(idx => ({
-        return { id: idx };
+        id: idx,
-    });
+    }));
 }
 
 const initialize_data = {

frontend_tests/node_tests/message_list_data.js

@@ -22,7 +22,7 @@ function make_msg(msg_id) {
 }
 
 function make_msgs(msg_ids) {
-    return _.map(msg_ids, make_msg);
+    return msg_ids.map(make_msg);
 }
 
 function assert_contents(mld, msg_ids) {

frontend_tests/node_tests/message_list_view.js

@@ -167,9 +167,7 @@ run_test('merge_message_groups', () => {
     }
 
     function extract_message_ids(lst) {
-        return _.map(lst, (item) => {
+        return lst.map(item => item.msg.id);
-            return item.msg.id;
-        });
     }
 
     function assert_message_list_equal(list1, list2) {
@@ -184,8 +182,8 @@ run_test('merge_message_groups', () => {
     }
 
     function assert_message_groups_list_equal(list1, list2) {
-        const ids1 = _.map(list1, extract_group);
+        const ids1 = list1.map(extract_group);
-        const ids2 = _.map(list2, extract_group);
+        const ids2 = list2.map(extract_group);
         assert(ids1.length);
         assert.deepEqual(ids1, ids2);
     }
@@ -547,11 +545,9 @@ run_test('render_windows', () => {
     let messages;
 
     function reset_list(opts) {
-        messages = _.map(_.range(opts.count), function (i) {
+        messages = _.range(opts.count).map(i => ({
-            return {
+            id: i,
-                id: i,
+        }));
-            };
-        });
         list.selected_idx = function () { return 0; };
         list.clear();
 

frontend_tests/node_tests/message_store.js

@@ -68,13 +68,11 @@ global.people.initialize_current_user(me.user_id);
 
 function convert_recipients(people) {
     // Display_recipient uses `id` for user_ids.
-    return _.map(people, (p) => {
+    return people.map(p => ({
-        return {
+        email: p.email,
-            email: p.email,
+        id: p.user_id,
-            id: p.user_id,
+        full_name: p.full_name,
-            full_name: p.full_name,
+    }));
-        };
-    });
 }
 
 run_test('add_message_metadata', () => {

frontend_tests/node_tests/narrow.js

@@ -15,9 +15,10 @@ set_global('page_params', {
 zrequire('narrow');
 
 function set_filter(operators) {
-    operators = _.map(operators, function (op) {
+    operators = operators.map(op => ({
-        return {operator: op[0], operand: op[1]};
+        operator: op[0],
-    });
+        operand: op[1],
+    }));
     narrow_state.set_current_filter(new Filter(operators));
 }
 

frontend_tests/node_tests/narrow_state.js

@@ -10,9 +10,10 @@ set_global('blueslip', global.make_zblueslip());
 set_global('page_params', {});
 
 function set_filter(operators) {
-    operators = _.map(operators, function (op) {
+    operators = operators.map(op => ({
-        return {operator: op[0], operand: op[1]};
+        operator: op[0],
-    });
+        operand: op[1],
+    }));
     narrow_state.set_current_filter(new Filter(operators));
 }
 

frontend_tests/node_tests/topic_list_data.js

@@ -82,9 +82,7 @@ run_test('get_list_info unreads', () => {
     // Going forward, we just stub get_recent_names
     // for simpler test setup.
     topic_data.get_recent_names = () => {
-        return _.map(_.range(15), (i) => {
+        return _.range(15).map(i => 'topic ' + i);
-            return 'topic ' + i;
-        });
     };
 
     const unread_cnt = {};
@@ -111,7 +109,7 @@ run_test('get_list_info unreads', () => {
     assert.equal(list_info.num_possible_topics, 15);
 
     assert.deepEqual(
-        _.map(list_info.items, (li) => li.topic_name),
+        list_info.items.map(li => li.topic_name),
         [
             'topic 0',
             'topic 1',
@@ -131,7 +129,7 @@ run_test('get_list_info unreads', () => {
     assert.equal(list_info.num_possible_topics, 15);
 
     assert.deepEqual(
-        _.map(list_info.items, (li) => li.topic_name),
+        list_info.items.map(li => li.topic_name),
         [
             'topic 0',
             'topic 1',
@@ -158,7 +156,7 @@ run_test('get_list_info unreads', () => {
     assert.equal(list_info.num_possible_topics, 15);
 
     assert.deepEqual(
-        _.map(list_info.items, (li) => li.topic_name),
+        list_info.items.map(li => li.topic_name),
         [
             'topic 0',
             'topic 1',

frontend_tests/node_tests/typeahead_helper.js

@@ -24,8 +24,8 @@ let next_id = 0;
 
 function assertSameEmails(lst1, lst2) {
     assert.deepEqual(
-        _.map(lst1, (r) => r.email),
+        lst1.map(r => r.email),
-        _.map(lst2, (r) => r.email)
+        lst2.map(r => r.email)
     );
 }
 
@@ -209,9 +209,7 @@ function get_typeahead_result(query, current_stream, current_topic) {
         current_stream,
         current_topic
     );
-    return _.map(result, function (person) {
+    return result.map(person => person.email);
-        return person.email;
-    });
 }
 
 run_test('sort_recipients', () => {
@@ -363,9 +361,7 @@ run_test('sort_recipients dup bots', () => {
     const dup_objects = matches.concat([a_bot]);
 
     const recipients = th.sort_recipients(dup_objects, "b", "", "");
-    const recipients_email = _.map(recipients, function (person) {
+    const recipients_email = recipients.map(person => person.email);
-        return person.email;
-    });
     const expected = [
         'b_bot@example.com',
         'b_user_3@zulip.net',
@@ -402,9 +398,7 @@ run_test('sort_recipients subscribers', () => {
     // b_user_2 is a subscriber and b_user_1 is not.
     const small_matches = [b_user_2, b_user_1];
     const recipients = th.sort_recipients(small_matches, "b", "Dev", "Dev Topic");
-    const recipients_email = _.map(recipients, function (person) {
+    const recipients_email = recipients.map(person => person.email);
-        return person.email;
-    });
     const expected = [
         'b_user_2@zulip.net',
         'b_user_1@zulip.net',
@@ -417,9 +411,7 @@ run_test('sort_recipients pm partners', () => {
     // both are not subscribered to the stream Linux.
     const small_matches = [b_user_3, b_user_2];
     const recipients = th.sort_recipients(small_matches, "b", "Linux", "Linux Topic");
-    const recipients_email = _.map(recipients, function (person) {
+    const recipients_email = recipients.map(person => person.email);
-        return person.email;
-    });
     const expected = [
         'b_user_3@zulip.net',
         'b_user_2@zulip.net',
@@ -438,7 +430,7 @@ run_test('sort broadcast mentions', () => {
         '');
 
     assert.deepEqual(
-        _.map(results, (r) => r.email),
+        results.map(r => r.email),
         ['all', 'everyone', 'stream']
     );
 
@@ -455,7 +447,7 @@ run_test('sort broadcast mentions', () => {
         '');
 
     assert.deepEqual(
-        _.map(results2, (r) => r.email),
+        results2.map(r => r.email),
         ['all',
          'everyone',
          'stream',
@@ -715,9 +707,7 @@ run_test('sort_slash_commands', () => {
 
 run_test('sort_recipientbox_typeahead', () => {
     let recipients = th.sort_recipientbox_typeahead("b, a", matches, ""); // search "a"
-    let recipients_email = _.map(recipients, function (person) {
+    let recipients_email = recipients.map(person => person.email);
-        return person.email;
-    });
     assert.deepEqual(recipients_email, [
         'a_user@zulip.org', // matches "a"
         'a_bot@zulip.com', // matches "a"
@@ -729,9 +719,7 @@ run_test('sort_recipientbox_typeahead', () => {
     ]);
 
     recipients = th.sort_recipientbox_typeahead("b, a, b", matches, ""); // search "b"
-    recipients_email = _.map(recipients, function (person) {
+    recipients_email = recipients.map(person => person.email);
-        return person.email;
-    });
     assert.deepEqual(recipients_email, [
         'b_bot@example.com',
         'b_user_3@zulip.net',

frontend_tests/node_tests/vdom.js

@@ -97,9 +97,7 @@ function make_child(i, name) {
 }
 
 function make_children(lst) {
-    return _.map(lst, (i) => {
+    return lst.map(i => make_child(i, 'foo' + i));
-        return make_child(i, 'foo' + i);
-    });
 }
 
 run_test('children', () => {

frontend_tests/zjsunit/i18n.js

@@ -17,7 +17,7 @@ exports.t = function (str, context) {
     */
     const keyword_regex = /__(- )?(\w)+__/g;
     const keys_in_str = str.match(keyword_regex) || [];
-    const substitutions = _.map(keys_in_str, function (key) {
+    const substitutions = keys_in_str.map(key => {
         let prefix_length;
         if (key.startsWith("__- ")) {
             prefix_length = 4;

frontend_tests/zjsunit/mdiff.js

@@ -118,7 +118,7 @@ function diff_strings(string_0, string_1) {
     const emphasize_codes = (string) => {
         return "\u001b[34m" + string.slice(0, 1) + "\u001b[0m" + string.slice(1);
     };
-    output_lines = _.map(output_lines, emphasize_codes);
+    output_lines = output_lines.map(emphasize_codes);
 
     return output_lines.join("\n");
 }

frontend_tests/zjsunit/zjquery.js

@@ -524,13 +524,9 @@ exports.make_zjquery = function (opts) {
 
     zjquery.state = function () {
         // useful for debugging
-        let res =  _.map(elems, function (v) {
+        let res =  elems.map(v => v.debug());
-            return v.debug();
-        });
 
-        res = _.map(res, function (v) {
+        res = res.map(v => [v.selector, v.value, v.shown]);
-            return [v.selector, v.value, v.shown];
-        });
 
         res.sort();
 

static/js/activity.js

@@ -128,15 +128,13 @@ exports.get_huddles = function () {
 };
 
 function huddle_split(huddle) {
-    return _.map(huddle.split(','), function (s) {
+    return huddle.split(',').map(s => parseInt(s, 10));
-        return parseInt(s, 10);
-    });
 }
 
 exports.full_huddle_name = function (huddle) {
     const user_ids = huddle_split(huddle);
 
-    const names = _.map(user_ids, function (user_id) {
+    const names = user_ids.map(user_id => {
         const person = people.get_by_user_id(user_id);
         return person.full_name;
     });
@@ -148,7 +146,7 @@ exports.short_huddle_name = function (huddle) {
     const user_ids = huddle_split(huddle);
 
     const num_to_show = 3;
-    let names = _.map(user_ids, function (user_id) {
+    let names = user_ids.map(user_id => {
         const person = people.get_by_user_id(user_id);
         return person.full_name;
     });
@@ -246,15 +244,13 @@ exports.update_huddles = function () {
         return;
     }
 
-    const group_pms = _.map(huddles, function (huddle) {
+    const group_pms = huddles.map(huddle => ({
-        return {
+        user_ids_string: huddle,
-            user_ids_string: huddle,
+        name: exports.full_huddle_name(huddle),
-            name: exports.full_huddle_name(huddle),
+        href: hash_util.huddle_with_uri(huddle),
-            href: hash_util.huddle_with_uri(huddle),
+        fraction_present: buddy_data.huddle_fraction_present(huddle),
-            fraction_present: buddy_data.huddle_fraction_present(huddle),
+        short_name: exports.short_huddle_name(huddle),
-            short_name: exports.short_huddle_name(huddle),
+    }));
-        };
-    });
 
     const html = render_group_pms({group_pms: group_pms});
     ui.get_content_element($('#group-pms')).html(html);

static/js/bot_data.js

@@ -26,9 +26,7 @@ exports.add = function bot_data__add(bot) {
     const clean_bot = _.pick(bot, bot_fields);
     bots.set(bot.user_id, clean_bot);
     set_can_admin(clean_bot);
-    const clean_services = _.map(bot.services, function (service) {
+    const clean_services = bot.services.map(service => _.pick(service, services_fields));
-        return _.pick(service, services_fields);
-    });
     services.set(bot.user_id, clean_services);
 
     send_change_event();

static/js/buddy_data.js

@@ -118,13 +118,9 @@ function filter_user_ids(filter_text, user_ids) {
     user_ids = _.reject(user_ids, people.is_my_user_id);
 
     let search_terms = filter_text.toLowerCase().split(/[|,]+/);
-    search_terms = _.map(search_terms, function (s) {
+    search_terms = search_terms.map(s => s.trim());
-        return s.trim();
-    });
 
-    const persons = _.map(user_ids, function (user_id) {
+    const persons = user_ids.map(user_id => people.get_by_user_id(user_id));
-        return people.get_by_user_id(user_id);
-    });
 
     const user_id_dict = people.filter_people_by_search_terms(persons, search_terms);
     return Array.from(user_id_dict.keys());
@@ -330,7 +326,7 @@ exports.get_filtered_and_sorted_user_ids = function (filter_text) {
 };
 
 exports.get_items_for_users = function (user_ids) {
-    const user_info = _.map(user_ids, exports.info_for);
+    const user_info = user_ids.map(exports.info_for);
     compose_fade.update_user_info(user_info, fade_config);
     return user_info;
 };

static/js/compose_ui.js

@@ -92,7 +92,7 @@ exports.compute_placeholder_text = function (opts) {
     // For Private Messages
     if (opts.private_message_recipient) {
         const recipient_list = opts.private_message_recipient.split(",");
-        const recipient_names = _.map(recipient_list, (recipient) => {
+        const recipient_names = recipient_list.map(recipient => {
             const user = people.get_by_email(recipient);
             return user.full_name;
         }).join(", ");

static/js/composebox_typeahead.js

@@ -325,19 +325,22 @@ exports.tokenize_compose_str = function (s) {
 };
 
 exports.broadcast_mentions = function () {
-    return _.map(['all', 'everyone', 'stream'], function (mention, idx) {
+    return ['all', 'everyone', 'stream'].map((mention, idx) => ({
-        return {
+        special_item_text: i18n.t("__wildcard_mention_token__ (Notify stream)",
-            special_item_text: i18n.t("__wildcard_mention_token__ (Notify stream)",
+                                  {wildcard_mention_token: mention}),
-                                      {wildcard_mention_token: mention}),
+
-            email: mention,
+        email: mention,
-            // Always sort above, under the assumption that names will
+
-            // be longer and only contain "all" as a substring.
+        // Always sort above, under the assumption that names will
-            pm_recipient_count: Infinity,
+        // be longer and only contain "all" as a substring.
-            full_name: mention,
+        pm_recipient_count: Infinity,
-            is_broadcast: true,
+
-            idx: idx, // used for sorting
+        full_name: mention,
-        };
+        is_broadcast: true,
-    });
+
+        // used for sorting
+        idx: idx,
+    }));
 };
 
 function filter_mention_name(current_token) {

static/js/drafts.js

@@ -228,7 +228,7 @@ exports.format_draft = function (draft) {
         };
     } else {
         const emails = util.extract_pm_recipients(draft.private_message_recipient);
-        const recipients = _.map(emails, function (email) {
+        const recipients = emails.map(email => {
             email = email.trim();
             const person = people.get_by_email(email);
             if (person !== undefined) {
@@ -305,7 +305,7 @@ exports.launch = function () {
             return draft_b.updatedAt - draft_a.updatedAt;
         });
 
-        const sorted_formatted_drafts = _.filter(_.map(sorted_raw_drafts, exports.format_draft));
+        const sorted_formatted_drafts = _.filter(sorted_raw_drafts.map(exports.format_draft));
 
         return sorted_formatted_drafts;
     }

static/js/echo.js

@@ -51,7 +51,7 @@ exports.build_display_recipient = function (message) {
     const emails = util.extract_pm_recipients(message.private_message_recipient);
 
     let sender_in_display_recipients = false;
-    const display_recipient = _.map(emails, function (email) {
+    const display_recipient = emails.map(email => {
         email = email.trim();
         const person = people.get_by_email(email);
         if (person === undefined) {

static/js/fenced_code.js

@@ -42,9 +42,7 @@ function wrap_quote(text) {
     // beginning of each line
     for (const paragraph of paragraphs) {
         const lines = paragraph.split('\n');
-        quoted_paragraphs.push(_.map(
+        quoted_paragraphs.push(_.reject(lines, function (line) { return line === ''; }).map(line => '> ' + line).join('\n'));
-            _.reject(lines, function (line) { return line === ''; }),
-            function (line) { return '> ' + line; }).join('\n'));
     }
 
     return quoted_paragraphs.join('\n\n');

static/js/filter.js

@@ -310,7 +310,7 @@ Filter.parse = function (str) {
    might need to support multiple operators of the same type.
 */
 Filter.unparse = function (operators) {
-    const parts = _.map(operators, function (elem) {
+    const parts = operators.map(elem => {
 
         if (elem.operator === 'search') {
             // Search terms are the catch-all case.
@@ -481,13 +481,11 @@ Filter.prototype = {
     },
 
     _canonicalize_operators: function (operators_mixed_case) {
-        return _.map(operators_mixed_case, function (tuple) {
+        return operators_mixed_case.map(tuple => Filter.canonicalize_term(tuple));
-            return Filter.canonicalize_term(tuple);
-        });
     },
 
     filter_with_new_topic: function (new_topic) {
-        const terms = _.map(this._operators, function (term) {
+        const terms = this._operators.map(term => {
             const new_term = _.clone(term);
             if (new_term.operator === 'topic' && !new_term.negated) {
                 new_term.operand = new_topic;
@@ -503,7 +501,7 @@ Filter.prototype = {
 
     sorted_term_types: function () {
         const terms = this._operators;
-        const term_types = _.map(terms, Filter.term_type);
+        const term_types = terms.map(Filter.term_type);
         const sorted_terms = Filter.sorted_term_types(term_types);
         return sorted_terms;
     },
@@ -712,7 +710,7 @@ function describe_unescaped(operators) {
         }
     }
 
-    const more_parts = _.map(operators, function (elem) {
+    const more_parts = operators.map(elem => {
         const operand = elem.operand;
         const canonicalized_operator = Filter.canonicalize_operator(elem.operator);
         if (canonicalized_operator === 'is') {

static/js/floating_recipient_bar.js

@@ -175,7 +175,7 @@ exports.relevant_recipient_bars = function () {
         return [];
     }
 
-    const items = _.map(elems, function (elem, i) {
+    const items = elems.map((elem, i) => {
         let date_html;
         let need_frb;
 

static/js/info_overlay.js

@@ -22,7 +22,7 @@ exports.set_up_toggler = function () {
     const elem = exports.toggler.get();
     elem.addClass('large allow-overflow');
 
-    const modals = _.map(opts.values, function (item) {
+    const modals = opts.values.map(item => {
         const key = item.key; // e.g. message-formatting
         const modal = $('#' + key).find('.modal-body');
         return modal;

static/js/message_events.js

@@ -34,7 +34,7 @@ function maybe_add_narrowed_messages(messages, msg_list) {
             // edited in between when they sent the message and when
             // we hear back from the server and can echo the new
             // message.  Arguably, it's counterproductive complexity.
-            new_messages = _.map(new_messages, message_store.add_message_metadata);
+            new_messages = new_messages.map(message_store.add_message_metadata);
 
             message_util.add_new_messages(new_messages, msg_list);
             unread_ops.process_visible();
@@ -54,7 +54,7 @@ function maybe_add_narrowed_messages(messages, msg_list) {
 
 
 exports.insert_new_messages = function insert_new_messages(messages, sent_by_this_client) {
-    messages = _.map(messages, message_store.add_message_metadata);
+    messages = messages.map(message_store.add_message_metadata);
 
     unread.process_loaded_messages(messages);
 

static/js/message_fetch.js

@@ -26,7 +26,7 @@ function process_result(data, opts) {
     }
 
     _.each(messages, message_store.set_message_booleans);
-    messages = _.map(messages, message_store.add_message_metadata);
+    messages = messages.map(message_store.add_message_metadata);
 
     // In case any of the newly fetched messages are new, add them to
     // our unread data structures.  It's important that this run even
@@ -118,7 +118,7 @@ function handle_operators_supporting_id_based_api(data) {
     }
 
     data.narrow = JSON.parse(data.narrow);
-    data.narrow = _.map(data.narrow, function (filter) {
+    data.narrow = data.narrow.map(filter => {
         if (operators_supporting_ids.includes(filter.operator)) {
             filter.operand = people.emails_strings_to_user_ids_array(filter.operand);
         }

static/js/message_flags.js

@@ -19,9 +19,7 @@ exports.send_read = (function () {
         const real_msgs = _.filter(queue, function (msg) {
             return !msg.locally_echoed;
         });
-        const real_msg_ids = _.map(real_msgs, function (msg) {
+        const real_msg_ids = real_msgs.map(msg => msg.id);
-            return msg.id;
-        });
 
         if (real_msg_ids.length === 0) {
             setTimeout(start, 100);

static/js/message_list_view.js

@@ -684,7 +684,7 @@ MessageListView.prototype = {
         // all messages lists. To prevent having both list views overwriting
         // each others data we will make a new message object to add data to
         // for rendering.
-        const message_containers = _.map(messages, function (message) {
+        const message_containers = messages.map(message => {
             if (message.starred) {
                 message.starred_status = i18n.t("Unstar");
             } else {
@@ -793,9 +793,7 @@ MessageListView.prototype = {
         if (message_actions.append_messages.length > 0) {
             last_message_row = table.find('.message_row').last().expectOne();
             last_group_row = rows.get_message_recipient_row(last_message_row);
-            dom_messages = $(_.map(message_actions.append_messages, function (message_container) {
+            dom_messages = $(message_actions.append_messages.map(message_container => self._get_message_template(message_container)).join('')).filter('.message_row');
-                return self._get_message_template(message_container);
-            }).join('')).filter('.message_row');
 
             self._post_process(dom_messages);
             last_group_row.append(dom_messages);
@@ -1233,9 +1231,7 @@ MessageListView.prototype = {
         const self = this;
 
         // Convert messages to list messages
-        let message_containers = _.map(messages, function (message) {
+        let message_containers = messages.map(message => self.message_containers[message.id]);
-            return self.message_containers[message.id];
-        });
         // We may not have the message_container if the stream or topic was muted
         message_containers = _.reject(message_containers, function (message_container) {
             return message_container === undefined;

static/js/message_store.js

@@ -39,7 +39,7 @@ exports.get_pm_emails = function (message) {
     }
 
     const user_ids = people.pm_with_user_ids(message);
-    const emails = _.map(user_ids, email).sort();
+    const emails = user_ids.map(email).sort();
 
     return emails.join(', ');
 };
@@ -56,7 +56,7 @@ exports.get_pm_full_names = function (message) {
     }
 
     const user_ids = people.pm_with_user_ids(message);
-    const names = _.map(user_ids, name).sort();
+    const names = user_ids.map(name).sort();
 
     return names.join(', ');
 };

static/js/narrow.js

@@ -115,8 +115,7 @@ exports.activate = function (raw_operators, opts) {
     notifications.hide_history_limit_message();
     $(".all-messages-search-caution").hide();
 
-    blueslip.debug("Narrowed", {operators: _.map(operators,
+    blueslip.debug("Narrowed", {operators: operators.map(e => e.operator),
-                                                 function (e) { return e.operator; }),
                                 trigger: opts ? opts.trigger : undefined,
                                 previous_id: current_msg_list.selected_id()});
 

static/js/people.js

@@ -38,9 +38,7 @@ exports.init = function () {
 exports.init();
 
 function split_to_ints(lst) {
-    return _.map(lst.split(','), function (s) {
+    return lst.split(',').map(s => parseInt(s, 10));
-        return parseInt(s, 10);
-    });
 }
 
 exports.get_by_user_id = function (user_id) {
@@ -137,9 +135,7 @@ exports.huddle_string = function (message) {
         return;
     }
 
-    let user_ids = _.map(message.display_recipient, function (recip) {
+    let user_ids = message.display_recipient.map(recip => recip.id);
-        return recip.id;
-    });
 
     function is_huddle_recip(user_id) {
         return user_id &&
@@ -161,11 +157,9 @@ exports.huddle_string = function (message) {
 exports.user_ids_string_to_emails_string = function (user_ids_string) {
     const user_ids = split_to_ints(user_ids_string);
 
-    let emails = _.map(user_ids, function (user_id) {
+    let emails = user_ids.map(user_id => {
         const person = people_by_user_id_dict.get(user_id);
-        if (person) {
+        return person && person.email;
-            return person.email;
-        }
     });
 
     if (!_.all(emails)) {
@@ -173,9 +167,7 @@ exports.user_ids_string_to_emails_string = function (user_ids_string) {
         return;
     }
 
-    emails = _.map(emails, function (email) {
+    emails = emails.map(email => email.toLowerCase());
-        return email.toLowerCase();
-    });
 
     emails.sort();
 
@@ -184,9 +176,7 @@ exports.user_ids_string_to_emails_string = function (user_ids_string) {
 
 exports.user_ids_string_to_ids_array = function (user_ids_string) {
     const user_ids = user_ids_string.split(',');
-    const ids = _.map(user_ids, function (id) {
+    const ids = user_ids.map(id => Number(id));
-        return Number(id);
-    });
     return ids;
 };
 
@@ -206,11 +196,9 @@ exports.reply_to_to_user_ids_string = function (emails_string) {
     // invalid data.
     const emails = emails_string.split(',');
 
-    let user_ids = _.map(emails, function (email) {
+    let user_ids = emails.map(email => {
         const person = exports.get_by_email(email);
-        if (person) {
+        return person && person.user_id;
-            return person.user_id;
-        }
     });
 
     if (!_.all(user_ids)) {
@@ -264,11 +252,9 @@ exports.emails_strings_to_user_ids_string = function (emails_string) {
 };
 
 exports.email_list_to_user_ids_string = function (emails) {
-    let user_ids = _.map(emails, function (email) {
+    let user_ids = emails.map(email => {
         const person = exports.get_by_email(email);
-        if (person) {
+        return person && person.user_id;
-            return person.user_id;
-        }
     });
 
     if (!_.all(user_ids)) {
@@ -282,11 +268,9 @@ exports.email_list_to_user_ids_string = function (emails) {
 };
 
 exports.safe_full_names = function (user_ids) {
-    let names = _.map(user_ids, function (user_id) {
+    let names = user_ids.map(user_id => {
         const person = people_by_user_id_dict.get(user_id);
-        if (person) {
+        return person && person.full_name;
-            return person.full_name;
-        }
     });
 
     names = _.filter(names);
@@ -309,7 +293,7 @@ exports.get_recipients = function (user_ids_string) {
         return exports.my_full_name();
     }
 
-    const names = _.map(other_ids, exports.get_full_name).sort();
+    const names = other_ids.map(exports.get_full_name).sort();
     return names.join(', ');
 };
 
@@ -330,7 +314,7 @@ exports.pm_reply_to = function (message) {
         return;
     }
 
-    const emails = _.map(user_ids, function (user_id) {
+    const emails = user_ids.map(user_id => {
         const person = people_by_user_id_dict.get(user_id);
         if (!person) {
             blueslip.error('Unknown user id in message: ' + user_id);
@@ -386,9 +370,7 @@ exports.all_user_ids_in_pm = function (message) {
         return;
     }
 
-    let user_ids = _.map(message.display_recipient, function (recip) {
+    let user_ids = message.display_recipient.map(recip => recip.id);
-        return recip.id;
-    });
 
     user_ids = sort_numerically(user_ids);
     return user_ids;
@@ -404,9 +386,7 @@ exports.pm_with_user_ids = function (message) {
         return;
     }
 
-    const user_ids = _.map(message.display_recipient, function (recip) {
+    const user_ids = message.display_recipient.map(recip => recip.id);
-        return recip.id;
-    });
 
     return sorted_other_user_ids(user_ids);
 };
@@ -421,9 +401,7 @@ exports.group_pm_with_user_ids = function (message) {
         return;
     }
 
-    const user_ids = _.map(message.display_recipient, function (recip) {
+    const user_ids = message.display_recipient.map(recip => recip.id);
-        return recip.id;
-    });
     const is_user_present = _.some(user_ids, function (user_id) {
         return exports.is_my_user_id(user_id);
     });
@@ -488,9 +466,7 @@ exports.update_email_in_reply_to = function (reply_to, user_id, new_email) {
     // and we don't warn on any errors.
     let emails = reply_to.split(',');
 
-    const persons = _.map(emails, function (email) {
+    const persons = emails.map(email => people_dict.get(email.trim()));
-        return people_dict.get(email.trim());
-    });
 
     if (!_.all(persons)) {
         return reply_to;
@@ -504,7 +480,7 @@ exports.update_email_in_reply_to = function (reply_to, user_id, new_email) {
         return reply_to;
     }
 
-    emails = _.map(persons, function (person) {
+    emails = persons.map(person => {
         if (person.user_id === user_id) {
             return new_email;
         }
@@ -516,10 +492,8 @@ exports.update_email_in_reply_to = function (reply_to, user_id, new_email) {
 
 exports.pm_with_operand_ids = function (operand) {
     let emails = operand.split(',');
-    emails = _.map(emails, function (email) { return email.trim(); });
+    emails = emails.map(email => email.trim());
-    let persons = _.map(emails, function (email) {
+    let persons = emails.map(email => people_dict.get(email));
-        return people_dict.get(email);
-    });
 
     // If your email is included in a PM group with other people, just ignore it
     if (persons.length > 1) {
@@ -530,9 +504,7 @@ exports.pm_with_operand_ids = function (operand) {
         return;
     }
 
-    let user_ids = _.map(persons, function (person) {
+    let user_ids = persons.map(person => person.user_id);
-        return person.user_id;
-    });
 
     user_ids = sort_numerically(user_ids);
 
@@ -788,9 +760,7 @@ exports.get_message_people = function () {
         semantics
     */
     const message_people = _.compact(
-        _.map(message_store.user_ids(), (user_id) => {
+        message_store.user_ids().map(user_id => people_by_user_id_dict.get(user_id))
-            return people_by_user_id_dict.get(user_id);
-        })
     );
 
     return message_people;
@@ -835,7 +805,7 @@ exports.build_person_matcher = function (query) {
     query = query.trim();
 
     const termlets = query.toLowerCase().split(/\s+/);
-    const termlet_matchers = _.map(termlets, exports.build_termlet_matcher);
+    const termlet_matchers = termlets.map(exports.build_termlet_matcher);
 
     return function (user) {
         const email = user.email.toLowerCase();
@@ -855,9 +825,7 @@ exports.filter_people_by_search_terms = function (users, search_terms) {
 
     // Build our matchers outside the loop to avoid some
     // search overhead that is not user-specific.
-    const matchers = _.map(search_terms, function (search_term) {
+    const matchers = search_terms.map(search_term => exports.build_person_matcher(search_term));
-        return exports.build_person_matcher(search_term);
-    });
 
     // Loop through users and populate filtered_users only
     // if they include search_terms

static/js/pm_list_dom.js

@@ -26,7 +26,7 @@ exports.pm_ul = (convos) => {
     ];
     return vdom.ul({
         attrs: attrs,
-        keyed_nodes: _.map(convos, exports.keyed_pm_li),
+        keyed_nodes: convos.map(exports.keyed_pm_li),
     });
 };
 

static/js/search_suggestion.js

@@ -45,11 +45,9 @@ function format_as_suggestion(terms) {
 }
 
 function compare_by_huddle(huddle) {
-    huddle = _.map(huddle.slice(0, -1), function (person) {
+    huddle = huddle.slice(0, -1).map(person => {
         person = people.get_by_email(person);
-        if (person) {
+        return person && person.user_id;
-            return person.user_id;
-        }
     });
 
     // Construct dict for all huddles, so we can lookup each's recency
@@ -99,7 +97,7 @@ function get_stream_suggestions(last, operators) {
     const regex = typeahead_helper.build_highlight_regex(query);
     const hilite = typeahead_helper.highlight_with_escaping_and_regex;
 
-    const objs = _.map(streams, function (stream) {
+    const objs = streams.map(stream => {
         const prefix = 'stream';
         const highlighted_stream = hilite(regex, stream);
         const verb = last.negated ? 'exclude ' : '';
@@ -160,7 +158,7 @@ function get_group_suggestions(last, operators) {
 
     const highlight_person = make_person_highlighter(last_part);
 
-    const suggestions = _.map(persons, function (person) {
+    const suggestions = persons.map(person => {
         const term = {
             operator: 'pm-with',
             operand: all_but_last_part + ',' + person.email,
@@ -240,7 +238,7 @@ function get_person_suggestions(people_getter, last, operators, autocomplete_ope
 
     const highlight_person = make_person_highlighter(query);
 
-    const objs = _.map(persons, function (person) {
+    const objs = persons.map(person => {
         const name = highlight_person(person);
         const description = prefix + ' ' + name;
         const terms = [{
@@ -363,7 +361,7 @@ function get_topic_suggestions(last, operators) {
     // care about case.
     topics.sort();
 
-    return _.map(topics, function (topic) {
+    return topics.map(topic => {
         const topic_term = {operator: 'topic', operand: topic, negated: negated};
         const operators = suggest_operators.concat([topic_term]);
         return format_as_suggestion(operators);
@@ -394,13 +392,11 @@ function get_special_filter_suggestions(last, operators, suggestions) {
     // Negating suggestions on is_search_operand_negated is required for
     // suggesting negated operators.
     if (last.negated || is_search_operand_negated) {
-        suggestions = _.map(suggestions, function (suggestion) {
+        suggestions = suggestions.map(suggestion => ({
-            return {
+            search_string: '-' + suggestion.search_string,
-                search_string: '-' + suggestion.search_string,
+            description: 'exclude ' + suggestion.description,
-                description: 'exclude ' + suggestion.description,
+            invalid: suggestion.invalid,
-                invalid: suggestion.invalid,
+        }));
-            };
-        });
     }
 
     const last_string = Filter.unparse([last]).toLowerCase();
@@ -583,7 +579,7 @@ function get_operator_suggestions(last) {
         return common.phrase_match(last_operand, choice);
     });
 
-    return _.map(choices, function (choice) {
+    return choices.map(choice => {
         const op = [{operator: choice, operand: '', negated: negated}];
         return format_as_suggestion(op);
     });
@@ -848,9 +844,7 @@ exports.finalize_search_result = function (result) {
         lookup_table[obj.search_string] = obj;
     }
 
-    const strings = _.map(result, function (obj) {
+    const strings = result.map(obj => obj.search_string);
-        return obj.search_string;
-    });
     return {
         strings: strings,
         lookup_table: lookup_table,

static/js/settings_org.js

@@ -373,9 +373,9 @@ exports.populate_realm_domains = function (realm_domains) {
         return;
     }
 
-    const domains_list = _.map(realm_domains, function (realm_domain) {
+    const domains_list = realm_domains.map(
-        return realm_domain.allow_subdomains ? "*." + realm_domain.domain : realm_domain.domain;
+        realm_domain => realm_domain.allow_subdomains ? "*." + realm_domain.domain : realm_domain.domain
-    });
+    );
     let domains = domains_list.join(', ');
     if (domains.length === 0) {
         domains = i18n.t("None");

static/js/stream_create.js

@@ -101,11 +101,9 @@ function ajaxSubscribeForCreation(stream_name, description, user_ids, invite_onl
                                   stream_post_policy, announce, history_public_to_subscribers) {
     // TODO: We can eliminate the user_ids -> principals conversion
     //       once we upgrade the backend to accept user_ids.
-    const persons = _.compact(_.map(user_ids, (user_id) => {
+    const persons = _.compact(user_ids.map(user_id => people.get_by_user_id(user_id)));
-        return people.get_by_user_id(user_id);
-    }));
 
-    const principals = _.map(persons, (person) => person.email);
+    const principals = persons.map(person => person.email);
 
     // Subscribe yourself and possible other people to a new stream.
     return channel.post({

static/js/stream_data.js

@@ -344,8 +344,8 @@ exports.get_invite_stream_data = function () {
             default_stream: exports.get_default_status(sub.name),
         };
     };
-    const invite_stream_data = _.map(exports.subscribed_subs(), filter_stream_data);
+    const invite_stream_data = exports.subscribed_subs().map(filter_stream_data);
-    const default_stream_data = _.map(page_params.realm_default_streams, filter_stream_data);
+    const default_stream_data = page_params.realm_default_streams.map(filter_stream_data);
 
     // Since, union doesn't work on array of objects we are using filter
     const is_included = {};
@@ -462,9 +462,7 @@ exports.home_view_stream_names = function () {
     const home_view_subs = _.filter(exports.subscribed_subs(), function (sub) {
         return !sub.is_muted;
     });
-    return _.map(home_view_subs, function (sub) {
+    return home_view_subs.map(sub => sub.name);
-        return sub.name;
-    });
 };
 
 exports.canonicalized_name = function (stream_name) {
@@ -571,7 +569,7 @@ exports.set_realm_default_streams = function (realm_default_streams) {
 };
 
 exports.get_default_stream_names = function () {
-    const streams = _.map(Array.from(default_stream_ids), exports.get_sub_by_id);
+    const streams = Array.from(default_stream_ids).map(exports.get_sub_by_id);
     const default_stream_names = _.pluck(streams, 'name');
     return default_stream_names;
 };

static/js/stream_sort.js

@@ -15,9 +15,7 @@ function filter_streams_by_search(streams, search_term) {
     }
 
     let search_terms = search_term.toLowerCase().split(",");
-    search_terms = _.map(search_terms, function (s) {
+    search_terms = search_terms.map(s => s.trim());
-        return s.trim();
-    });
 
     const filtered_streams = _.filter(streams, function (stream) {
         return _.any(search_terms, function (search_term) {

static/js/submessage.js

@@ -15,12 +15,10 @@ exports.get_message_events = function (message) {
         return parseInt(m1.id, 10) - parseInt(m2.id, 10);
     });
 
-    const events = _.map(message.submessages, function (obj) {
+    const events = message.submessages.map(obj => ({
-        return {
+        sender_id: obj.sender_id,
-            sender_id: obj.sender_id,
+        data: JSON.parse(obj.content),
-            data: JSON.parse(obj.content),
+    }));
-        };
-    });
 
     return events;
 };

static/js/tab_bar.js

@@ -61,7 +61,7 @@ function make_tab_data() {
 
             if (filter.has_operator("pm-with")) {
                 const emails = filter.operands("pm-with")[0].split(',');
-                const names = _.map(emails, function (email) {
+                const names = emails.map(email => {
                     if (!people.get_by_email(email)) {
                         return email;
                     }

static/js/topic_data.js

@@ -154,9 +154,7 @@ exports.topic_history = function (stream_id) {
             return b.message_id - a.message_id;
         });
 
-        const names = _.map(recents, function (obj) {
+        const names = recents.map(obj => obj.pretty_name);
-            return obj.pretty_name;
-        });
 
         return names;
     };

static/js/topic_list.js

@@ -136,8 +136,7 @@ exports.widget = function (parent_elem, my_stream_id) {
             ['class', 'topic-list'],
         ];
 
-        const nodes = _.map(
+        const nodes = list_info.items.map(exports.keyed_topic_li);
-            list_info.items, exports.keyed_topic_li);
 
         if (spinner) {
             nodes.push(exports.spinner_li());

static/js/unread.js

@@ -283,7 +283,7 @@ exports.unread_topic_counter = (function () {
             return topic_dict.has(topic_name);
         });
 
-        const result = _.map(topic_names, function (topic_name) {
+        const result = topic_names.map(topic_name => {
             const msgs = per_stream_bucketer.get_bucket(topic_name);
 
             return {

static/js/util.js

@@ -107,8 +107,8 @@ exports.normalize_recipients = function (recipients) {
     // Converts a string listing emails of message recipients
     // into a canonical formatting: emails sorted ASCIIbetically
     // with exactly one comma and no spaces between each.
-    recipients = _.map(recipients.split(','), function (s) { return s.trim(); });
+    recipients = recipients.split(',').map(s => s.trim());
-    recipients = _.map(recipients, function (s) { return s.toLowerCase(); });
+    recipients = recipients.map(s => s.toLowerCase());
     recipients = _.filter(recipients, function (s) { return s.length > 0; });
     recipients.sort();
     return recipients.join(',');
@@ -249,7 +249,7 @@ function to_int(s) {
 exports.sorted_ids = function (ids) {
     // This mapping makes sure we are using ints, and
     // it also makes sure we don't mutate the list.
-    let id_list = _.map(ids, to_int);
+    let id_list = ids.map(to_int);
     id_list.sort(function (a, b) {
         return a - b;
     });

static/js/vdom.js

@@ -39,9 +39,7 @@ exports.render_tag = (tag) => {
     */
     const opts = tag.opts;
     const tag_name = tag.tag_name;
-    const attr_str = _.map(opts.attrs, (attr) => {
+    const attr_str = opts.attrs.map(attr => ' ' + attr[0] + '="' + util.escape_html(attr[1]) + '"').join('');
-        return ' ' + attr[0] + '="' + util.escape_html(attr[1]) + '"';
-    }).join('');
 
     const start_tag = '<' + tag_name + attr_str + '>';
     const end_tag = '</' + tag_name + '>';
@@ -51,9 +49,7 @@ exports.render_tag = (tag) => {
         return;
     }
 
-    const innards = _.map(opts.keyed_nodes, (node) => {
+    const innards = opts.keyed_nodes.map(node => node.render()).join('\n');
-        return node.render();
-    }).join('\n');
     return start_tag + '\n' + innards + '\n' + end_tag;
 };