Merge ff644b1 into 4ad23b1

src/collection.js

@@ -209,6 +209,35 @@ export default class Collection {
 		return item || null;
 	}
 
+	/**
+	 * Returns a boolean indicating whether the collection contains an item. Item id or index can be used instead of the
+	 * item.
+	 *
+	 * @param {Object|String|Number} itemOrIdOrIndex The item, item id or item index in the collection.
+	 * @returns {Boolean} `true` if the collection contains the item, `false` otherwise.
+	 */
+	has( itemOrIdOrIndex ) {
+		if ( typeof itemOrIdOrIndex == 'number' ) {
+			return !!this._items[ itemOrIdOrIndex ];
+		} else if ( typeof itemOrIdOrIndex == 'string' ) {
+			return this._itemMap.has( itemOrIdOrIndex );
+		} else { // Object
+			const idProperty = this._idProperty;
+			const id = itemOrIdOrIndex[ idProperty ];
+
+			if ( typeof id != 'string' ) {
+				/**
+				 * This item's id should be a string.
+				 *
+				 * @error collection-has-invalid-id
+				 */
+				throw new CKEditorError( 'collection-has-invalid-id: This item\'s id should be a string.' );
+			}
+
+			return this._itemMap.has( id );
+		}
+	}
+
 	/**
 	 * Gets index of item in the collection.
 	 * When item is not defined in the collection then index will be equal -1.

tests/collection.js

@@ -321,6 +321,56 @@ describe( 'Collection', () => {
 		} );
 	} );
 
+	describe( 'has()', () => {
+		it( 'should return true if collection contains item with given id', () => {
+			collection.add( getItem( 'foo' ) );
+
+			expect( collection.has( 'foo' ) ).to.equal( true );
+		} );
+
+		it( 'should return false if collection does not contain item with given id', () => {
+			collection.add( getItem( 'foo' ) );
+
+			expect( collection.has( 'bar' ) ).to.equal( false );
+		} );
+
+		it( 'should return true if collection contains item on index', () => {
+			collection.add( getItem( 'foo' ) );
+			collection.add( getItem( 'bar' ) );
+
+			expect( collection.has( 0 ) ).to.equal( true );
+			expect( collection.has( 1 ) ).to.equal( true );
+		} );
+
+		it( 'should return false if collection does not contain item on index', () => {
+			collection.add( getItem( 'foo' ) );
+			collection.add( getItem( 'bar' ) );
+
+			expect( collection.has( -1 ) ).to.equal( false );
+			expect( collection.has( 2 ) ).to.equal( false );
+		} );
+
+		it( 'should return true if collection contains item', () => {
+			const item = getItem( 'foo' );
+
+			collection.add( item );
+
+			expect( collection.has( item ) ).to.equal( true );
+		} );
+
+		it( 'should return false if collection does not contains item', () => {
+			collection.add( getItem( 'foo' ) );
+
+			expect( collection.has( getItem( 'bar' ) ) ).to.equal( false );
+		} );
+
+		it( 'should throw if an object without id is given', () => {
+			expect( () => {
+				collection.has( {} );
+			} ).to.throw( CKEditorError, /^collection-has-invalid-id/ );
+		} );
+	} );
+
 	describe( 'getIndex()', () => {
 		it( 'should return index of given item', () => {
 			const item1 = { foo: 'bar' };