feat(tree): enable custom filter of query

documents/src/pages/elements/combo-box.md

@@ -218,25 +218,29 @@ comboBox.data = [
   { label: 'Brazil', value: 'br' },
   { label: 'Argentina', value: 'ar' }
 ];
-const customFilter = (comboBox) => {
+const createCustomFilter = (comboBox) => {
   let query = '';
   let queryRegExp;
   const getRegularExpressionOfQuery = () => {
     if (comboBox.query !== query || !queryRegExp) {
       query = comboBox.query || '';
+      // Non-word characters are escaped to prevent ReDoS attack.
+      // This serves as a demo only. 
+      // For production, use a proven implementation instead.
       queryRegExp = new RegExp(query.replace(/(\W)/g, '\\$1'), 'i');
     }
     return queryRegExp;
   };
   return (item) => {
+    const label = item.label;
+    const value = item.value;
     const regex = getRegularExpressionOfQuery();
-    const result = query === item.value || regex.test(item.label);
-    regex.lastIndex = 0; // do not forget to reset last index
+    const result =  regex.test(value) || regex.test(label);
     return result;
   };
 };
 
-comboBox.filter = customFilter(comboBox);
+comboBox.filter = createCustomFilter(comboBox);
 ```
 ```css
 .wrapper {
@@ -255,7 +259,7 @@ comboBox.filter = customFilter(comboBox);
 const comboBox = document.querySelector('ef-combo-box');
 
 // Make a scoped re-usable filter for performance
-const customFilter = (comboBox) => {
+const createCustomFilter = (comboBox) => {
   let query = ''; // reference query string for validating queryRegExp cache state
   let queryRegExp; // cache RegExp
 
@@ -265,25 +269,28 @@ const customFilter = (comboBox) => {
   const getRegularExpressionOfQuery = () => {
     if (comboBox.query !== query || !queryRegExp) {
       query = comboBox.query || '';
+      // Non-word characters are escaped to prevent ReDoS attack.
+      // This serves as a demo only. 
+      // For production, use a proven implementation instead.
       queryRegExp = new RegExp(query.replace(/(\W)/g, '\\$1'), 'i');
     }
     return queryRegExp;
   };
 
   // return scoped custom filter
   return (item) => {
+    const label = item.label;
+    const value = item.value;
     const regex = getRegularExpressionOfQuery();
-    const result = query === item.value || regex.test(item.label);
-    regex.lastIndex = 0; // do not forget to reset last index
+    const result = regex.test(value) || regex.test(label);
     return result;
   };
 };
 
-comboBox.filter = customFilter(comboBox);
+comboBox.filter = createCustomFilter(comboBox);
 ```
 
-
-@> Regardless of filter configuration Combo Box always treats `type: 'header'` items as group headers, which persist as long as at least one item within the group is visible.
+@> Regardless of filter configuration, Combo Box always treats `type: 'header'` items as group headers, which persist as long as at least one item within the group is visible.
 
 ## Asynchronous filtering
 
@@ -345,6 +352,9 @@ comboBox.filter = null;
 
 // A function to make request. In real life scenario it may wrap fetch
 const request = (query, value) => {
+  // Non-word characters are escaped to prevent ReDoS attack.
+  // This serves as a demo only. 
+  // For production, use a proven implementation instead.
   const regex = new RegExp(query.replace(/(\W)/g, '\\$1'), 'i');
 
   // Always keep a promise to let Combo Box know that the data is loading
@@ -360,13 +370,11 @@ const request = (query, value) => {
             selected: true,
             hidden: query ? !regex.test(item.label) : false
           }));
-          regex.lastIndex = 0;
           continue;
         }
 
         if (query && regex.test(item.label)) {
           filterData.push(item);
-          regex.lastIndex = 0;
         }
       }
     }

documents/src/pages/elements/tree-select.md

@@ -300,12 +300,10 @@ setTimeout(() => { el.opened = true; }, 1000);
 *> If the number of selected items is likely to be large, pills may not be a good choice for display or performance.
 
 ## Filtering
-Tree select has built in text filtering and selection editing.
 
-By clicking the `Selected` button, Tree Select allows the items to be filtered by selected state, and that subset to be operated on in isolation from the main item list.
-
-For custom filtering, Tree Select provides an identical interface as Combo Box. You provide a predicate function that tests an item. Please consult the [Combo Box docs](./elements/combo-box) for details on how to construct a compatible filter.
+Tree Select has built in text filtering and selection editing. By clicking the `Selected` button, Tree Select allows the items to be filtered by selected state, and that subset to be operated on in isolation from the main item list.
 
+For custom filtering, Tree Select provides an identical interface as Combo Box. You provide a predicate function testing each item. Please consult the [Combo Box docs](./elements/combo-box#filtering) for details on how to construct a compatible filter.
 
 ## Limiting Selected Items
 Tree Select offers a convenient way to limit the number of selected items using `max` property. If users attempt to select more items than the specified limit, "Done" button will be automatically disabled.

documents/src/pages/elements/tree.md

@@ -361,7 +361,122 @@ tree.addEventListener('value-changed', (event) => {
 });
 ```
 
+## Filtering
+
+Filtering happens when `query` property or attribute is not empty. By Default, the filter is applied on the data `label` property. Developers may wish to do their own filtering by implementing the `filter` property. A typical example is to apply filter on multiple data properties e.g. `label` and `value`.
+
+::
+```javascript
+::import-elements::
+const tree = document.querySelector('ef-tree');
+tree.data = [
+  { label: 'EMEA', value: 'emea', expanded: true, items: [
+    { label: 'France', value: 'fr' },
+    { label: 'Russian Federation', value: 'ru' },
+    { label: 'Spain', value: 'es' },
+    { label: 'United Kingdom', value: 'gb' }
+  ]},
+  { label: 'APAC', value: 'apac', expanded: true, items: [
+    { label: 'China', value: 'ch' },
+    { label: 'Australia', value: 'au' },
+    { label: 'India', value: 'in' },
+    { label: 'Thailand', value: 'th' }
+  ]},
+  { label: 'AMERS', value: 'amers', expanded: true, items: [
+    { label: 'Canada', value: 'ca' },
+    { label: 'United States', value: 'us' },
+    { label: 'Brazil', value: 'br' },
+    { label: 'Argentina', value: 'ar' }
+  ]}
+];
+const createCustomFilter = (tree) => {
+  let query = '';
+  let queryRegExp;
+  const getRegularExpressionOfQuery = () => {
+    if (tree.query !== query || !queryRegExp) {
+      query = tree.query || '';
+      // Non-word characters are escaped to prevent ReDoS attack.
+      // This serves as a demo only. 
+      // For production, use a proven implementation instead.
+      queryRegExp = new RegExp(query.replace(/(\W)/g, '\\$1'), 'i');
+    }
+    return queryRegExp;
+  };
+  return (item) => {
+    const label = item.label;
+    const value = item.value;
+    const regex = getRegularExpressionOfQuery();
+    const result = regex.test(value) || regex.test(label);
+    return result;
+  };
+};
+tree.filter = createCustomFilter(tree);
+
+const input = document.getElementById('query');
+input.addEventListener('value-changed', e => {
+  tree.query = e.detail.value;
+});
+```
+```css
+.wrapper {
+  padding: 5px;
+  width: 300px;
+  height: 430px;
+}
+
+#query {
+  width: 200px;
+}
+```
+```html
+<div class="wrapper">
+  <label for="query">Filter</label>
+  <ef-text-field id="query" placeholder="keyword to filter Tree's items"></ef-text-field>
+  <br>
+  <ef-tree></ef-tree>
+</div>
+```
+::
+
+```javascript
+const tree = document.querySelector('ef-tree');
+
+// Make a scoped re-usable filter for performance
+const createCustomFilter = (tree) => {
+  let query = ''; // reference query string for validating queryRegExp cache state
+  let queryRegExp; // cache RegExp
+
+  // Get current RegExp, or renew if out of date
+  // this is fetched on demand by filter/renderer
+  // only created once per query
+  const getRegularExpressionOfQuery = () => {
+    if (tree.query !== query || !queryRegExp) {
+      query = tree.query || '';
+      // Non-word characters are escaped to prevent ReDoS attack.
+      // This serves as a demo only. 
+      // For production, use a proven implementation instead.
+      queryRegExp = new RegExp(query.replace(/(\W)/g, '\\$1'), 'i');
+    }
+    return queryRegExp;
+  };
+
+  // return scoped custom filter
+  return (item) => {
+    const label = item.label;
+    const value = item.value;
+    const regex = getRegularExpressionOfQuery();
+    const result = regex.test(value) || regex.test(label);
+    return result;
+  };
+};
+
+tree.filter = createCustomFilter(tree);
+```
+
+@> Regardless of filter configuration, Tree always shows parent items as long as at least one of their child is visible.
+
 ## Accessibility
+
 ::a11y-intro::
 
 `ef-tree` is assigned `role="tree"` and can include properties such as `aria-multiselectable`, `aria-label`, or `aria-labelledby`. It receives focus once at host and it is navigable through items using `Up` and `Down` arrow keys and expandable or collapsable using `Left` and `Right`. Each item is assigned `role="treeitem"` and can include properties such as `aria-selected` or `aria-checked` in `multiple` mode. 

packages/elements/src/combo-box/__demo__/index.html

@@ -156,7 +156,6 @@
             const regex = getRegularExpressionOfQuery();
             // test on label or value
             const result = query === item.value || regex.test(item.label);
-            regex.lastIndex = 0; // do not forget to reset last index
             return result;
           };
         };
@@ -297,13 +296,11 @@
                         hidden: query ? !regex.test(item.label) : false
                       })
                     );
-                    regex.lastIndex = 0;
                     continue;
                   }
 
                   if (query && regex.test(item.label)) {
                     filterData.push(item);
-                    regex.lastIndex = 0;
                   }
                 }
               }

packages/elements/src/combo-box/__snapshots__/Filter.md

@@ -67,9 +67,69 @@
     </ef-list-item>
   </ef-list>
 </ef-overlay>
+```
 
+```html
+<div part="input-wrapper">
+  <input
+    aria-activedescendant="AX"
+    aria-autocomplete="list"
+    aria-expanded="true"
+    aria-haspopup="listbox"
+    aria-owns="internal-list"
+    autocomplete="off"
+    part="input"
+    role="combobox"
+    type="text"
+  >
+  <div
+    id="toggle-button"
+    part="button button-toggle"
+  >
+    <ef-icon
+      icon="down"
+      part="icon icon-toggle"
+    >
+    </ef-icon>
+  </div>
+</div>
+<ef-overlay-viewport>
+</ef-overlay-viewport>
+<ef-overlay
+  first-resize-done=""
+  no-autofocus=""
+  no-focus-management=""
+  no-overlap=""
+  opened=""
+  part="list"
+  tabindex="-1"
+  with-shadow=""
+>
+  <ef-list
+    aria-multiselectable="false"
+    id="internal-list"
+    role="listbox"
+    tabindex=""
+  >
+    <ef-list-item
+      aria-selected="false"
+      role="presentation"
+      type="header"
+    >
+    </ef-list-item>
+    <ef-list-item
+      aria-selected="false"
+      highlighted=""
+      id="AX"
+      role="option"
+    >
+    </ef-list-item>
+  </ef-list>
+</ef-overlay>
 ```
 
+####   `Should be able to use custom filter function`
+
 ```html
 <div part="input-wrapper">
   <input

packages/elements/src/combo-box/__test__/combo-box.filter.test.js

@@ -1,3 +1,5 @@
+import escapeStringRegexp from 'escape-string-regexp';
+
 import '@refinitiv-ui/elements/combo-box';
 
 import '@refinitiv-ui/elemental-theme/light/ef-combo-box';
@@ -31,5 +33,37 @@ describe('combo-box/Filter', function () {
       expect(el.query).to.equal(textInput, 'Query should be the same as input text: "Aland Islands"');
       expect(el).shadowDom.to.equalSnapshot(snapshotIgnore);
     });
+
+    it('Should be able to use custom filter function', async function () {
+      const el = await fixture('<ef-combo-box opened></ef-combo-box>');
+      el.data = getData();
+      await elementUpdated(el);
+
+      const createCustomFilter = (comboBox) => {
+        let query = '';
+        let queryRegExp;
+        // Items could be filtered with case-insensitive partial match of both labels & values.
+        const getRegularExpressionOfQuery = () => {
+          if (comboBox.query !== query || !queryRegExp) {
+            query = comboBox.query || '';
+            queryRegExp = new RegExp(escapeStringRegexp(query), 'i');
+          }
+          return queryRegExp;
+        };
+        return (item) => {
+          const value = item.value;
+          const label = item.label;
+          const regex = getRegularExpressionOfQuery();
+          const result = regex.test(value) || regex.test(label);
+          return result;
+        };
+      };
+      el.filter = createCustomFilter(el);
+      const textInput = 'ax';
+      await setInputEl(el, textInput);
+      await elementUpdated(el);
+      expect(el.query).to.equal(textInput, `Query should be the same as input text: "${textInput}"`);
+      await expect(el).shadowDom.to.equalSnapshot(snapshotIgnore);
+    });
   });
 });

packages/elements/src/combo-box/helpers/filter.ts

@@ -11,7 +11,7 @@ import type { ComboBoxFilter } from './types';
  * @param el ComboBox instance to filter
  * @returns Filter accepting an item
  */
-export const defaultFilter = <T extends DataItem = ItemData>(el: ComboBox<T>): ComboBoxFilter<T> => {
+export const createDefaultFilter = <T extends DataItem = ItemData>(el: ComboBox<T>): ComboBoxFilter<T> => {
   // reference query string for validating queryRegExp cache state
   let query = '';
   // cache RegExp
@@ -32,8 +32,6 @@ export const defaultFilter = <T extends DataItem = ItemData>(el: ComboBox<T>): C
   return (item): boolean => {
     const regex = getRegularExpressionOfQuery();
     const result = regex.test((item as unknown as ItemText).label);
-    // this example uses global scope, so the index needs resetting
-    regex.lastIndex = 0;
     return result;
   };
 };