为什么显示是1 跟 0

<!DOCTYPE html>

<html>


<head>

<meta charset="utf-8" />

<meta http-equiv="X-UA-Compatible" content="IE=edge">

<title>Page Title</title>

<meta name="viewport" content="width=device-width, initial-scale=1">

<script>

window.onload = function() {

var len1 = getByClass('on', 'list');

alert(len1.length); // 结果等于2为正确

var len2 = getByClass('on');

alert(len2.length); // 结果等于3为正确

}


function getByClass(clsName, parent) {

//定义函数getByClass

var oP = parent ? document.getElementById(parent) : document;

//是一个判断语句,如果传入parent即parent存在,那么var op = document.getElementById(parent),不存在的话就是var op = document

var a = oP.getElementsByTagName('*');

var b = new Array();

for (var i = 0; i < a.length; i++) {

if (a[i].className == clsName) {

b.push(a[i]);

}

return b;

}

}

</script>

</head>


<body>

<ul id="list">

<li class="on">1</li>

<li class="select">2</li>

<li class="on">3</li>

<li>4</li>

</ul>

<p class="on">class为on的p标签</p>

</body>


</html>


阿尼加得
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1回答

__innocence

return b 需要放在for循环外面。

慕瓜9220888

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