feat(facade/collections): add fill ponyfill to ListWrapper

src/facade/collections.ts

@@ -317,9 +317,62 @@ export class ListWrapper {
 
   static isEmpty( list: any[] ): boolean { return list.length == 0; }
 
-  //static fill(list: any[], value: any, start: number = 0, end: number = null) {
-  //  list.fill(value, start, end === null ? list.length : end);
-  //}
+  static fill( list: any[], value: any, start: number = 0, end: number = null ) {
+
+    if ( !(Array.prototype as any).fill ) {
+      (Array.prototype as any).fill = function ( value ) {
+
+        // Steps 1-2.
+        if ( this == null ) {
+          throw new TypeError( 'this is null or not defined' );
+        }
+
+        var O = Object( this );
+
+        // Steps 3-5.
+        var len = O.length >>> 0;
+
+        // Steps 6-7.
+        var start = arguments[ 1 ];
+        var relativeStart = start >> 0;
+
+        // Step 8.
+        var k = relativeStart < 0
+          ? Math.max( len + relativeStart, 0 )
+          : Math.min( relativeStart, len );
+
+        // Steps 9-10.
+        var end = arguments[ 2 ];
+        var relativeEnd = end === undefined
+          ? len
+          : end >> 0;
+
+        // Step 11.
+        var final = relativeEnd < 0
+          ? Math.max( len + relativeEnd, 0 )
+          : Math.min( relativeEnd, len );
+
+        // Step 12.
+        while ( k < final ) {
+          O[ k ] = value;
+          k++;
+        }
+
+        // Step 13.
+        return O;
+      };
+    }
+
+    (list as any).fill(
+      value,
+      start,
+      end === null
+        ? list.length
+        : end
+    );
+
+  }
+
   static equals( a: any[], b: any[] ): boolean {
     if ( a.length != b.length ) return false;
     for ( var i = 0; i < a.length; ++i ) {

test/facade/collections.spec.ts

@@ -173,6 +173,29 @@ describe( `facade/collections`, ()=> {
 
       } );
 
+      it( `should fill array with provided value`, () => {
+
+        let arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4 );
+        expect( arr ).to.deep.equal( [ 4, 4, 4 ] );
+        arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4, 1 );
+        expect( arr ).to.deep.equal( [ 1, 4, 4 ] );
+        arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4, 1, 2 );
+        expect( arr ).to.deep.equal( [ 1, 4, 3 ] );
+        arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4, 1, 1 );
+        expect( arr ).to.deep.equal( [ 1, 2, 3 ] );
+        arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4, -3, -2 );
+        expect( arr ).to.deep.equal( [ 4, 2, 3 ] );
+        arr = [ 1, 2, 3 ];
+        ListWrapper.fill( arr, 4, NaN, NaN );
+        expect( arr ).to.deep.equal( [ 1, 2, 3 ] );
+
+      } );
+
     } );
 
   } );