为什么我得到TypeError：obj.addEventListener不是函数？

问题描述

这是我的代码：

function addEvent( obj, type, fn ) {
  if ( obj.attachEvent ) {
    obj['e'+type+fn] = fn;
    obj[type+fn] = function(){obj['e'+type+fn]( window.event );}
    obj.attachEvent( 'on'+type, obj[type+fn] );
  } else
    obj.addEventListener(type, fn, false);
}

function alertWinner(){
    alert("You may be a winner!");
}

function showWinner (){
    var aTag = document.getElementsByTagName("a");
    addEvent(aTag, 'click', alertWinner);
}

showWinner();

基本上，我正在使用firebug控制台并尝试在任何时候弹出警报点击一个标签。

Basically, I'm working in the firebug console and trying to get an alert to pop up when any a tag is clicked.

我看不出导致这种情况不起作用的问题，并且在我的问题标题中给出了错误（在firebug中查看）。有人吗？

I can't see the problem that results in this not working and giving me the error stated in my questions title (viewed in firebug). Anybody?

推荐答案

document.getElementsByTagName 返回。每个元素都有一个 addEventListener 函数，但该数组没有。

document.getElementsByTagName returns a NodeList of DOM elements. Each element has an addEventListener function, but the array doesn't have one.

循环遍历：

function showWinner (){
    var aTags = document.getElementsByTagName("a");
    for (var i=0;i<aTags.length;i++){
        addEvent(aTags[i], 'click', alertWinner);
    }
}

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