Question

我遇到addEventListener问题。当我点击第三个div标签时，它不会改变背景颜色，警报也不起作用。

这是我的html结构：

<!DOCTYPE html>
<html>
<head>
  <script type="text/javascript"  src="myscript.js"></script>
</head>
<body>
  <p>Click the button to display an alert box:</p>
  <div>Robert</div>
  <div>Arthur</div>
  <div>Procedure(Third)</div>
  <div>Fourth</div>
  <button onclick="myfunc()">Try it</button>
</body>

这是javascript文件：

var Ar = ["red", "yellow", "green", "blue"]

function getRandomInt(min, max)
{
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

function myfunc() {
    alert(getRandomInt(0,5));

}

function Group(handler) {
    var R = [];
    for (var I = 0, E = document.getElementsByTagName('div'), L = E.length; I < L; I++) {
        handler && handler.call(E[I]);
        if (!handler)
            R.push(E[I]);
     }
    return R;
 }

 //get third div tags and set a handler
 Group()[2].addEventListener("click", handler, false);

function handler() {
    alert("Test!"); 
    Group()[2].style.backgroundColor = Ar[getRandomInt(0,3)];   
 }

Answer 1

您正在尝试在加载元素之前访问这些元素。

在页面末尾包含您的脚本，它将起作用。

<!DOCTYPE html>
<html>
<head>

</head>
<body>
  <p>Click the button to display an alert box:</p>
  <div>Robert</div>
  <div>Arthur</div>
  <div>Procedure(Third)</div>
  <div>Fourth</div>
  <button onclick="myfunc()">Try it</button>
</body>
<script type="text/javascript"  src="myscript.js"></script>

Answer 2

像这样修改你的代码。

<body>
    <p>Click the button to display an alert box:</p>
    <div>Robert</div>
    <div>Arthur</div>
    <div>Procedure(Third)</div>
    <div>Fourth</div>
    <button onclick="myfunc()">Try it</button>
    <script type="text/javascript">
        Group()[2].addEventListener("click", handler, false);
    </script>
</body>

addEventListener不起作用

2 个答案: