emoji: Refactor `get_emoji_details_by_name` function.

This is a prep commit for typescript migration of `emoji.js`. This
commit refactors the code for generating emoji rendering details such
that we avoid writing an ugly code which will involve writing an
incomplete type object when we migrate to TypeScript.

web/src/emoji.js

@@ -217,29 +217,27 @@ export function get_emoji_details_by_name(emoji_name) {
         throw new Error("Emoji name must be passed.");
     }
 
-    const emoji_info = {emoji_name};
-
     if (active_realm_emojis.has(emoji_name)) {
-        if (emoji_name === "zulip") {
-            emoji_info.reaction_type = "zulip_extra_emoji";
-        } else {
-            emoji_info.reaction_type = "realm_emoji";
-        }
         const emoji_code_info = active_realm_emojis.get(emoji_name);
-        emoji_info.emoji_code = emoji_code_info.id;
-        emoji_info.url = emoji_code_info.emoji_url;
-        if (emoji_code_info.still_url) {
-            emoji_info.still_url = emoji_code_info.still_url;
-        }
-    } else {
-        const codepoint = get_emoji_codepoint(emoji_name);
-        if (codepoint === undefined) {
-            throw new Error("Bad emoji name: " + emoji_name);
-        }
-        emoji_info.reaction_type = "unicode_emoji";
-        emoji_info.emoji_code = codepoint;
+        return {
+            emoji_name,
+            emoji_code: emoji_code_info.id,
+            url: emoji_code_info.emoji_url,
+            still_url: emoji_code_info.still_url,
+            reaction_type: emoji_name === "zulip" ? "zulip_extra_emoji" : "realm_emoji",
+        };
     }
-    return emoji_info;
+
+    const codepoint = get_emoji_codepoint(emoji_name);
+    if (codepoint === undefined) {
+        throw new Error("Bad emoji name: " + emoji_name);
+    }
+
+    return {
+        emoji_name,
+        reaction_type: "unicode_emoji",
+        emoji_code: codepoint,
+    };
 }
 
 export function get_emoji_details_for_rendering(opts) {

web/tests/emoji.test.js

@@ -76,6 +76,7 @@ run_test("get_emoji_details_by_name", () => {
         reaction_type: "zulip_extra_emoji",
         emoji_code: "zulip",
         url: "/static/generated/emoji/images/emoji/unicode/zulip.png",
+        still_url: null,
     });
 
     // Test adding realm emoji.
@@ -97,6 +98,7 @@ run_test("get_emoji_details_by_name", () => {
         reaction_type: "realm_emoji",
         emoji_code: "102",
         url: "/some/path/to/emoji",
+        still_url: null,
     });
 
     // Test sending without emoji name.

web/tests/reactions.test.js

@@ -358,6 +358,7 @@ test("sending", ({override, override_rewire}) => {
             reaction_type: "zulip_extra_emoji",
             emoji_name: "zulip",
             emoji_code: "zulip",
+            still_url: null,
             url: "/static/generated/emoji/images/emoji/unicode/zulip.png",
         });
     }