js 实现class作为选择器

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="智能社 - zhinengshe.com" />
<meta name="copyright" content="智能社 - zhinengshe.com" />
<title>智能社 - www.zhinengshe.com</title>

<script>

function findInArr(arr,n){
    for(var i=0;i<arr.length;i++){
        if(arr[i] == n){
            return true;
        }
    }
    return false;
}


function getByClass(oParent,sClass){
    
    var ret = [];
    
    var aEle = oParent.getElementsByTagName("*");
    console.log(aEle)
    for(var i = 0; i < aEle.length; i++){
        
        var _aTmp = aEle[i].className.split(" ");
        if(findInArr(_aTmp,sClass)){
            ret.push(aEle[i]);
        }
    }
    return ret;
}

window.onload = function(){
    var oDiv = document.getElementById("div1");
    
    var aBox = getByClass(document,"box");
    
    alert(aBox.length);
    
        
};



</script>
</head>

<body>

<div id="div1" class="box">
    <ul>
        <li class="box  active btn bnt1"></li>
        <li class="box"></li>
        <li></li>
        <li class="btn"></li>
    </ul>

</div>


</body>
</html>
原文地址:https://www.cnblogs.com/heboliufengjie/p/4750260.html