list_widget: Make `get_item` option required and pass a default where needed.

This is a prep commit for moving towards typescript migration of this module.
We should make `get_item` required on `list_widget` because its intended to be
used with a set of keys and then hydrate the keys lazily. Also this will help
us to avoid writing messy if-conditions while filtering and sorting and make
our life much easier when we migrate to TypeScript.

I added a `default_get_item` function which is just n identity function and
also refactored some code to make use of default get item.

web/src/alert_words_ui.js

@@ -23,6 +23,7 @@ export function rerender_alert_words_ui() {
 
     ListWidget.create($word_list, words, {
         name: "alert-words-list",
+        get_item: ListWidget.default_get_item,
         modifier(alert_word) {
             return render_alert_word_settings_item({alert_word});
         },

web/src/attachments_ui.js

@@ -94,6 +94,7 @@ function render_attachments_ui() {
 
     ListWidget.create($uploaded_files_table, attachments, {
         name: "uploaded-files-list",
+        get_item: ListWidget.default_get_item,
         modifier(attachment) {
             return render_uploaded_files_list({attachment});
         },

web/src/dropdown_list_widget.js

@@ -116,6 +116,7 @@ export class DropdownListWidget {
 
         this.list_widget = ListWidget.create($dropdown_list_body, this.get_data(data), {
             name: `${CSS.escape(this.widget_name)}_list`,
+            get_item: ListWidget.default_get_item,
             modifier(item) {
                 return render_dropdown_list({item});
             },
@@ -414,6 +415,7 @@ export class MultiSelectDropdownListWidget extends DropdownListWidget {
 
         this.list_widget = ListWidget.create($dropdown_list_body, data, {
             name: `${CSS.escape(this.widget_name)}_list`,
+            get_item: ListWidget.default_get_item,
             modifier(item) {
                 return render_dropdown_list({item});
             },

web/src/dropdown_widget.js

@@ -47,6 +47,7 @@ export function setup(tippy_props, get_options, item_click_callback, dropdown_pr
 
             const list_widget = ListWidget.create($dropdown_list_body, get_options(), {
                 name: `${CSS.escape(tippy_props.target)}-list-widget`,
+                get_item: ListWidget.default_get_item,
                 modifier(item) {
                     return render_dropdown_list({item});
                 },

web/src/list_widget.js

@@ -24,6 +24,10 @@ export function validate_opts(opts) {
         blueslip.error("$simplebar_container is missing.");
         return false;
     }
+    if (!opts.get_item) {
+        blueslip.error("get_item is missing.");
+        return false;
+    }
     return true;
 }
 
@@ -36,25 +40,18 @@ export function get_filtered_items(value, list, opts) {
     const get_item = opts.get_item;
 
     if (!opts.filter) {
-        if (get_item) {
         return list.map((key) => get_item(key));
     }
-        return [...list];
-    }
 
     if (opts.filter.filterer) {
-        if (get_item) {
         return opts.filter.filterer(
             list.map((key) => get_item(key)),
             value,
         );
     }
-        return opts.filter.filterer(list, value);
-    }
 
     const predicate = (item) => opts.filter.predicate(item, value);
 
-    if (get_item) {
     const result = [];
 
     for (const key of list) {
@@ -65,9 +62,6 @@ export function get_filtered_items(value, list, opts) {
     }
 
     return result;
-    }
-
-    return list.filter((item) => predicate(item));
 }
 
 export function alphabetic_sort(prop) {
@@ -262,9 +256,7 @@ export function create($container, list, opts) {
                 return;
             }
 
-            if (opts.get_item) {
             item = opts.get_item(item);
-            }
             const html = opts.modifier(item);
             if (typeof html !== "string") {
                 blueslip.error("List item is not a string", {item: html});
@@ -495,3 +487,5 @@ export function handle_sort($th, list) {
     // and not if it is undefined.
     list.sort(sort_type, prop_name);
 }
+
+export const default_get_item = (item) => item;

web/src/recent_topics_ui.js

@@ -843,6 +843,7 @@ export function complete_rerender() {
     $container.empty();
     topics_widget = ListWidget.create($container, mapped_topic_values, {
         name: "recent_topics_table",
+        get_item: ListWidget.default_get_item,
         $parent_container: $("#recent_topics_table"),
         modifier(item) {
             return render_recent_topic_row(format_conversation(item));

web/src/settings_emoji.js

@@ -111,6 +111,7 @@ export function populate_emoji() {
     const $emoji_table = $("#admin_emoji_table").expectOne();
     ListWidget.create($emoji_table, Object.values(emoji_data), {
         name: "emoji_list",
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             if (item.deactivated !== true) {
                 return render_admin_emoji_list({

web/src/settings_exports.js

@@ -41,6 +41,7 @@ export function populate_exports_table(exports) {
     const $exports_table = $("#admin_exports_table").expectOne();
     ListWidget.create($exports_table, Object.values(exports), {
         name: "admin_exports_list",
+        get_item: ListWidget.default_get_item,
         modifier(data) {
             let failed_timestamp = data.failed_timestamp;
             let deleted_timestamp = data.deleted_timestamp;

web/src/settings_invites.js

@@ -61,6 +61,7 @@ function populate_invites(invites_data) {
     const $invites_table = $("#admin_invites_table").expectOne();
     ListWidget.create($invites_table, invites_data.invites, {
         name: "admin_invites_list",
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             item.invited_absolute_time = timerender.absolute_time(item.invited * 1000);
             if (item.expiry_date !== null) {

web/src/settings_linkifiers.js

@@ -136,6 +136,7 @@ export function populate_linkifiers(linkifiers_data) {
     const $linkifiers_table = $("#admin_linkifiers_table").expectOne();
     ListWidget.create($linkifiers_table, linkifiers_data, {
         name: "linkifiers_list",
+        get_item: ListWidget.default_get_item,
         modifier(linkifier) {
             return render_admin_linkifier_list({
                 linkifier: {

web/src/settings_muted_users.js

@@ -21,6 +21,7 @@ export function populate_list() {
 
     ListWidget.create($muted_users_table, all_muted_users, {
         name: "muted-users-list",
+        get_item: ListWidget.default_get_item,
         modifier(muted_user) {
             return render_muted_user_ui_row({muted_user});
         },

web/src/settings_playgrounds.js

@@ -35,6 +35,7 @@ export function populate_playgrounds(playgrounds_data) {
     const $playgrounds_table = $("#admin_playgrounds_table").expectOne();
     ListWidget.create($playgrounds_table, playgrounds_data, {
         name: "playgrounds_list",
+        get_item: ListWidget.default_get_item,
         modifier(playground) {
             return render_admin_playground_list({
                 playground: {

web/src/settings_streams.js

@@ -108,6 +108,7 @@ export function build_default_stream_table() {
 
     ListWidget.create($table, subs, {
         name: "default_streams_list",
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             return render_admin_default_streams_list({
                 stream: item,

web/src/settings_user_topics.js

@@ -25,6 +25,7 @@ export function populate_list() {
 
     ListWidget.create($user_topics_table, all_user_topics, {
         name: "user-topics-list",
+        get_item: ListWidget.default_get_item,
         modifier(user_topic) {
             const context = {
                 user_topic,

web/src/stream_edit_subscribers.js

@@ -112,6 +112,7 @@ function make_list_widget({$parent_container, name, user_ids, user_can_remove_su
 
     return ListWidget.create($list_container, users, {
         name,
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             return format_member_list_elem(item, user_can_remove_subscribers);
         },

web/src/user_group_edit_members.js

@@ -66,6 +66,7 @@ function make_list_widget({$parent_container, name, user_ids}) {
 
     return ListWidget.create($list_container, users, {
         name,
+        get_item: ListWidget.default_get_item,
         $parent_container,
         sort_fields: {
             email: settings_users.sort_email,

web/src/user_groups_settings_ui.js

@@ -199,6 +199,7 @@ export function setup_page(callback) {
 
         group_list_widget = ListWidget.create($container, user_groups_list, {
             name: "user-groups-overlay",
+            get_item: ListWidget.default_get_item,
             modifier(item) {
                 item.is_member = user_groups.is_direct_member_of(
                     people.my_current_user_id(),

web/src/user_profile.js

@@ -83,6 +83,7 @@ function render_user_stream_list(streams, user) {
     $container.empty();
     ListWidget.create($container, streams, {
         name: `user-${user.user_id}-stream-list`,
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             return format_user_stream_list_item(item, user);
         },
@@ -102,6 +103,7 @@ function render_user_group_list(groups, user) {
     $container.empty();
     ListWidget.create($container, groups, {
         name: `user-${user.user_id}-group-list`,
+        get_item: ListWidget.default_get_item,
         modifier(item) {
             return format_user_group_list_item(item);
         },

web/tests/list_widget.test.js

@@ -157,6 +157,7 @@ run_test("scrolling", () => {
 
     const opts = {
         modifier: (item) => item,
+        get_item: (item) => item,
         $simplebar_container: $scroll_container,
     };
 
@@ -205,6 +206,7 @@ run_test("not_scrolling", () => {
 
     const opts = {
         modifier: (item) => item,
+        get_item: (item) => item,
         $simplebar_container: $scroll_container,
         is_scroll_position_for_render: () => false,
         post_scroll__pre_render_callback,
@@ -243,6 +245,7 @@ run_test("filtering", () => {
             predicate: (item, value) => item.includes(value),
         },
         modifier: (item) => div(item),
+        get_item: (item) => item,
         $simplebar_container: $scroll_container,
     };
 
@@ -288,6 +291,7 @@ run_test("no filtering", () => {
         callback_after_render() {
             callback_called = true;
         },
+        get_item: (item) => item,
     };
     const widget = ListWidget.create($container, ["apple", "banana"], opts);
     widget.render();
@@ -362,6 +366,7 @@ run_test("wire up filter element", () => {
             $element: $filter_element,
         },
         modifier: (s) => "(" + s + ")",
+        get_item: (item) => item,
         $simplebar_container: $scroll_container,
     };
 
@@ -392,6 +397,7 @@ run_test("sorting", () => {
         name: "sorting-list",
         $parent_container: $sort_container,
         modifier: (item) => div(item.name) + div(item.salary),
+        get_item: (item) => item,
         filter: {
             predicate: () => true,
         },
@@ -492,6 +498,7 @@ run_test("custom sort", () => {
     ListWidget.create($container, list, {
         name: "custom-sort-list",
         modifier: (n) => "(" + n.x + ", " + n.y + ")",
+        get_item: (item) => item,
         sort_fields: {
             product: sort_by_product,
             x_value: sort_by_x,
@@ -529,6 +536,7 @@ run_test("clear_event_handlers", () => {
         name: "list-we-create-twice",
         $parent_container: $sort_container,
         modifier() {},
+        get_item() {},
         filter: {
             $element: $filter_element,
             predicate: /* istanbul ignore next */ () => true,
@@ -578,6 +586,7 @@ run_test("errors", () => {
             predicate: "wrong type",
         },
         $simplebar_container: $scroll_container,
+        get_item() {},
     });
     blueslip.reset();
 
@@ -588,6 +597,7 @@ run_test("errors", () => {
             predicate: /* istanbul ignore next */ () => true,
         },
         $simplebar_container: $scroll_container,
+        get_item() {},
     });
     blueslip.reset();
 
@@ -595,6 +605,7 @@ run_test("errors", () => {
     ListWidget.create($container, list, {
         filter: {},
         $simplebar_container: $scroll_container,
+        get_item() {},
     });
     blueslip.reset();
 
@@ -602,6 +613,7 @@ run_test("errors", () => {
     ListWidget.create($container, list, {
         modifier: () => 999,
         $simplebar_container: $scroll_container,
+        get_item: (item) => item,
     });
     blueslip.reset();
 });
@@ -638,6 +650,7 @@ run_test("replace_list_data w/filter update", () => {
     ListWidget.create($container, list, {
         name: "replace-list",
         modifier: (n) => "(" + n.toString() + ")",
+        get_item: (item) => item,
         filter: {
             predicate: (n) => n % 2 === 0,
             onupdate() {
@@ -873,6 +886,7 @@ run_test("Multiselect dropdown retain_selected_items", () => {
     const widget = ListWidget.create($container, list, {
         name: "replace-list",
         modifier: (item) => `<li data-value="${item.value}">${item.name}</li>\n`,
+        get_item: (item) => item,
         multiselect: {
             selected_items: data,
         },