Can't seem to add the Background

cocos2d-x JavaScript
#1

First method, this works

var layer1 = cc.LayerColor.create(new cc.Color4B(20, 139, 159, 255), 400, 600);

layer1.setAnchorPoint(new cc.Point(0.5,0.5));
this.addChild(layer1);

Second method, this doesn’t work
var background= new Background();
this.addChild(background);

var Background=cc.Layer.extend({
init:function()
{
this._super();
var s = cc.Director.getInstance().getWinSize();

var layer = cc.LayerColor.create(cc.c4b(20, 139, 159, 255), 400, 600);
layer.ignoreAnchorPointForPosition(false);
layer.setPosition(cc.p(s.width / 2, s.height / 2));
this.addChild(layer, 1, 1);
why the second method doesn’t work?