refactor: Move is to traversing, optimize

src/api/attributes.spec.ts

@@ -1028,56 +1028,4 @@ describe('$(...)', () => {
       );
     });
   });
-
-  describe('.is', () => {
-    it('() : should return false', () => {
-      expect($('li.apple').is()).toBe(false);
-    });
-
-    it('(true selector) : should return true', () => {
-      expect(cheerio('#vegetables', vegetables).is('ul')).toBe(true);
-    });
-
-    it('(false selector) : should return false', () => {
-      expect(cheerio('#vegetables', vegetables).is('div')).toBe(false);
-    });
-
-    it('(true selection) : should return true', () => {
-      const $vegetables = cheerio('li', vegetables);
-      expect($vegetables.is($vegetables.eq(1))).toBe(true);
-    });
-
-    it('(false selection) : should return false', () => {
-      const $vegetableList = cheerio(vegetables);
-      const $vegetables = $vegetableList.find('li');
-      expect($vegetables.is($vegetableList)).toBe(false);
-    });
-
-    it('(true element) : should return true', () => {
-      const $vegetables = cheerio('li', vegetables);
-      expect($vegetables.is($vegetables[0])).toBe(true);
-    });
-
-    it('(false element) : should return false', () => {
-      const $vegetableList = cheerio(vegetables);
-      const $vegetables = $vegetableList.find('li');
-      expect($vegetables.is($vegetableList[0])).toBe(false);
-    });
-
-    it('(true predicate) : should return true', () => {
-      const result = $('li').is(function () {
-        return this.tagName === 'li' && $(this).hasClass('pear');
-      });
-      expect(result).toBe(true);
-    });
-
-    it('(false predicate) : should return false', () => {
-      const result = $('li')
-        .last()
-        .is(function () {
-          return this.tagName === 'ul';
-        });
-      expect(result).toBe(false);
-    });
-  });
 });

src/api/attributes.ts

@@ -8,7 +8,6 @@ import { text } from '../static';
 import { isTag, domEach, camelCase, cssCase } from '../utils';
 import type { Node, Element } from 'domhandler';
 import type { Cheerio } from '../cheerio';
-import { AcceptedFilters } from '../types';
 const hasOwn = Object.prototype.hasOwnProperty;
 const rspace = /\s+/;
 const dataAttrPrefix = 'data-';
@@ -1000,25 +999,3 @@ export function toggleClass<T extends Node, R extends ArrayLike<T>>(
 
   return this;
 }
-
-/**
- * Checks the current list of elements and returns `true` if *any* of the
- * elements match the selector. If using an element or Cheerio selection,
- * returns `true` if *any* of the elements match. If using a predicate function,
- * the function is executed in the context of the selected element, so `this`
- * refers to the current element.
- *
- * @category Attributes
- * @param selector - Selector for the selection.
- * @returns Whether or not the selector matches an element of the instance.
- * @see {@link https://api.jquery.com/is/}
- */
-export function is<T>(
-  this: Cheerio<T>,
-  selector?: AcceptedFilters<T>
-): boolean {
-  if (selector) {
-    return this.filter(selector).length > 0;
-  }
-  return false;
-}

src/api/traversing.spec.ts

@@ -9,6 +9,7 @@ import {
   text,
   forms,
   mixedText,
+  vegetables,
 } from '../__fixtures__/fixtures';
 
 function getText(el: Cheerio<Element>) {
@@ -1528,4 +1529,56 @@ describe('$(...)', () => {
       expect($div.addBack()).toBe($div);
     });
   });
+
+  describe('.is', () => {
+    it('() : should return false', () => {
+      expect($('li.apple').is()).toBe(false);
+    });
+
+    it('(true selector) : should return true', () => {
+      expect(cheerio('#vegetables', vegetables).is('ul')).toBe(true);
+    });
+
+    it('(false selector) : should return false', () => {
+      expect(cheerio('#vegetables', vegetables).is('div')).toBe(false);
+    });
+
+    it('(true selection) : should return true', () => {
+      const $vegetables = cheerio('li', vegetables);
+      expect($vegetables.is($vegetables.eq(1))).toBe(true);
+    });
+
+    it('(false selection) : should return false', () => {
+      const $vegetableList = cheerio(vegetables);
+      const $vegetables = $vegetableList.find('li');
+      expect($vegetables.is($vegetableList)).toBe(false);
+    });
+
+    it('(true element) : should return true', () => {
+      const $vegetables = cheerio('li', vegetables);
+      expect($vegetables.is($vegetables[0])).toBe(true);
+    });
+
+    it('(false element) : should return false', () => {
+      const $vegetableList = cheerio(vegetables);
+      const $vegetables = $vegetableList.find('li');
+      expect($vegetables.is($vegetableList[0])).toBe(false);
+    });
+
+    it('(true predicate) : should return true', () => {
+      const result = $('li').is(function () {
+        return this.tagName === 'li' && $(this).hasClass('pear');
+      });
+      expect(result).toBe(true);
+    });
+
+    it('(false predicate) : should return false', () => {
+      const result = $('li')
+        .last()
+        .is(function () {
+          return this.tagName === 'ul';
+        });
+      expect(result).toBe(false);
+    });
+  });
 });

src/api/traversing.ts

@@ -683,9 +683,7 @@ function getFilterFn<T>(
   match: FilterFunction<T> | Cheerio<T> | T
 ): (el: T, i: number) => boolean {
   if (typeof match === 'function') {
-    return function (el, i) {
-      return (match as FilterFunction<T>).call(el, i, el);
-    };
+    return (el, i) => (match as FilterFunction<T>).call(el, i, el);
   }
   if (isCheerio<T>(match)) {
     return (el) => match.is(el);
@@ -799,6 +797,34 @@ export function filter<T>(
   return container._make<unknown>(result);
 }
 
+/**
+ * Checks the current list of elements and returns `true` if *any* of the
+ * elements match the selector. If using an element or Cheerio selection,
+ * returns `true` if *any* of the elements match. If using a predicate function,
+ * the function is executed in the context of the selected element, so `this`
+ * refers to the current element.
+ *
+ * @category Attributes
+ * @param selector - Selector for the selection.
+ * @returns Whether or not the selector matches an element of the instance.
+ * @see {@link https://api.jquery.com/is/}
+ */
+export function is<T>(
+  this: Cheerio<T>,
+  selector?: AcceptedFilters<T>
+): boolean {
+  const nodes = this.toArray();
+  return typeof selector === 'string'
+    ? select.some(
+        (nodes as unknown as Node[]).filter(isTag),
+        selector,
+        this.options
+      )
+    : selector
+    ? nodes.some(getFilterFn<T>(selector))
+    : false;
+}
+
 /**
  * Remove elements from the set of matched elements. Given a Cheerio object that
  * represents a set of DOM elements, the `.not()` method constructs a new