Question

<div id="id1">Click to know</div>

<script>
function Superheroe(power){
    this.power=power;
}
//edited: copy mistake solved
Superheroe.prototype.sayYourPower=function(){
    alert('This is my power :'+ this.power);
}

var Mike = new Superheroe ("Code fast");


document.getElementById('id1').addEventListener("click",Mike.sayYourPower);
</script>

我想知道为什么我会得到＆＃39; undefined＆＃39;当我要求sayYourPower时......不包括＆＃34;（）＆＃34;在方法的最后？

Answer 1

您的Superhero对象尚未扩展Person原型，因此Mike没有函数sayYourPower。

Answer 2

您应该使用Superheroe代替Person，并使用bind函数或匿名函数作为处理程序，用于savinf上下文

＆＃13;

function Superheroe(power){
    this.power=power;
}

Superheroe.prototype.sayYourPower=function(){
    alert('This is my power :'+ this.power);
}

var Mike = new Superheroe ("Code fast");


document.getElementById('id1').addEventListener("click",Mike.sayYourPower.bind(Mike));
//another variant with anonymous function
//document.getElementById('id1').addEventListener("click",function(){Mike.sayYourPower()});

＆＃13;

<div id="id1">Click to know</div>

＆＃13;

javascript测试中的简单原型

2 个答案: