var s1Div = document.getElementById("s1Div"); Button: { var Button = function(btnName){ this.btnName = btnName; } Button.prototype.tap = function(){ s1Div.textContent += this.btnName + "が押されました。"; } } BlinkButton: { var BlinkButton = function(btnName){ Button.call(this, btnName); this.btnName = btnName; } BlinkButton.prototype = Object.create(Button.prototype,{ value: { constructor: BlinkButton } }); BlinkButton.prototype.tap = function(){ Button.prototype.tap.call(this); s1Div.textContent += "点滅しました"; } } var btn1 = new Button("ふつうのボタン"); var btn2 = new Button("点滅するボタン"); btn1.tap(); btn2.tap();