ts: Convert message_parser module to TypeScript.

static/js/message_parser.ts

@@ -1,23 +1,29 @@
 // We only use jquery for parsing.
 import $ from "jquery";
 
+// TODO: Move this to message_store when it is
+// converted to TypeScript.
+interface Message {
+    content: string;
+}
+
 // We need to check if the message content contains the specified HTML
 // elements.  We wrap the message.content in a <div>; this is
 // important because $("Text <a>link</a>").find("a") returns nothing;
 // one needs an outer element wrapping an object to use this
 // construction.
-function is_element_in_message_content(message, element_selector) {
+function is_element_in_message_content(message: Message, element_selector: string): boolean {
     return $(`<div>${message.content}</div>`).find(`${element_selector}`).length > 0;
 }
 
-export function message_has_link(message) {
+export function message_has_link(message: Message): boolean {
     return is_element_in_message_content(message, "a");
 }
 
-export function message_has_image(message) {
+export function message_has_image(message: Message): boolean {
     return is_element_in_message_content(message, ".message_inline_image");
 }
 
-export function message_has_attachment(message) {
+export function message_has_attachment(message: Message): boolean {
     return is_element_in_message_content(message, "a[href^='/user_uploads']");
 }