这段代码的运行结果为什么是undefined
<!DOCTYPE html>
<html dir="ltr">
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<div class="name">
<div class="">
<span>
<img src="" alt="">
</span>
</div>
</div>
</body>
<script type="text/javascript">
function getNum(ele,box,num){
var num = num ? num : 1;
if(ele.parentNode == box){
return num;// num = 4
}else{
num++;
getNum(ele.parentNode,box,num);
}
}
var a = document.getElementsByTagName("img")[0];
var b = document.getElementsByTagName("body")[0];
var c = getNum(a,b);
console.log(c);
</script>
</html>
繁星coding浏览 557回答 3
3回答
-
UYOU
function getNum(ele,box,num){ var num = num ? num : 1; if(ele.parentNode == box){ return num;// num = 4 }else{ num++; return getNum(ele.parentNode,box,num); } } var a = document.getElementsByTagName("img")[0]; var b = document.getElementsByTagName("body")[0]; var c = getNum(a,b); console.log(c);不符合条件的话没return出去东西啊 -
拉莫斯之舞
你else也要return getNum另外 var num = num ? num : 1 最好写成 function(ele,box,num = 1){} -
尚方宝剑之说
<script>//假设elem是target的意向父元素function getParentOfBodyNum( elem, target, num ) { var num = num ? num : 1; if ( elem.parentNode == target ) { document.write( "一共查找" + num + "次");//在html中，如果单单return num，并没有可见结果 } else { num ++; return getParentOfBodyNum( elem.parentNode, target, num ); }}var image = document.getElementsByTagName( "img" )[ 0 ];var body = document.getElementsByTagName( "body" )[ 0 ];getParentOfBodyNum( image, body );</script>
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相关分类
JavaScript