li上点击事件没有效果，朋友们帮我看看我的哪里出现了问题
点击无法打钩，点击事件无用 代码哪里出了问题
<!DOCTYPE html>
<html>
<head>
<link rel="shortcut icon" type="Img/icon" href="抽屉.ico">
<meta charset="UTF-8">
<title>复选框美化</title>
<style type="text/css">
*{padding: 0;margin:0;}
li{list-style: none;}
body{font:13px/26px "微软雅黑"}
.typeList {width: 500px;height: 28px;border: 0.5px solid #666;border-width: 1px 0;margin: 66px auto}
.typeList ul{height: 30px;line-height: 30px;overflow: hidden;}
.typeList ul li{float: left;padding-left: 25px;position: relative;}
.typeList input{display: none;}
.typeList b{display:block;width: 20px;height: 20px;background: url(Img/checkbox.gif) no-repeat -12px -17px;position: absolute;top: 4px}
.typeList ul li label{margin-left: 20px}
.typeList ul li:hover b{background-position:-12px -217px;}
.typeList ul .selected b,.typeList ul .selected:hover b{background-position: -12px -317px;}
</style>
<script src="JavaScript/同时页面加载多个.js"></script>
<script type="text/javascript">
function insert(){
var li = document.getElementById("checkList").getElementsByTagName("li");
var label = document.getElementById("checkList").getElementsByTagName("label");
for (var i = 0; i < li.length;i++) {
//var label = li[i].getElementsByTagName('label');
var tagB=document.createElement("b");
li[i].insertBefore(tagB,label[i]);
}
}
function selected(){
var li=document.getElementById("checkList").getElementsByTagName("li");
for(var i=0;i<i.length;i++){
var b = li[i].getElementsByTagName('b');
li[i].onclick=function(){
// b[0].style.backgroundPosition="-12px -217px";
if(this.className=="selected"){
this.className=null;
}else{
this.className="selected";
}
}
}
}
addLoadEvent(insert);
addLoadEvent(selected);
</script>
</head>
<body>
<div>
<form action="#">
<ul id="checkList">
<li><input type="checkbox" id="HW"><label for="HW">华为</label></li>
<li><input type="checkbox" id="XM"><label for="XM">小米</label></li>
<li><input type="checkbox" id="SS"><label for="SS">三星</label></li>
<li><input type="checkbox" id="OP"><label for="OP">OPPO</label></li>
<li><input type="checkbox" id="VV"><label for="VV">ViVO</label></li>
<li><input type="checkbox" id="MZ"><label for="MZ">魅族</label></li>
<li><input type="checkbox" id="IP"><label for="IP">苹果</label></li>
</ul>
</form>
</div>
</body>
</html>
