如何确定对象是否具有某些元素的子元素？

Question

I have a very simple function, which I want to work only if selected object has child of certain type - in this case if it has ul nested. 我有一个非常简单的函数，只有在选定对象具有某种类型的子对象的情况下，我才想使用它-在这种情况下，如果它具有ul嵌套。

I have tried with this: 我已经尝试过：

var onMouseOver = function() {
 if (this.getElementsByTagName('ul') > 0);{
   console.log('entered');
 }
}

and this: 和这个：

var onMouseOver = function() {
 if (this.querySelector('ul') != null);{
   console.log('enter');
 }
}

but it doesn't help - function still launches, even when it returnes 'null'. 但这无济于事-即使返回“ null”，功能仍会启动。

Answer 1

You should be looking at the length property of those selectors. 您应该查看这些选择器的length属性。

 var onMouseOver = function() { if (this.querySelectorAll('ul').length > 0);{ console.log('enter'); } }

or 要么

 var onMouseOver = function() { if (this.getElementsByTagName('ul').length > 0);{ console.log('entered'); } }

Answer 2

try this one :) 试试这个:)

 function ok(obj) { var l = obj.children.length; for (var i = 0; i <= l; i++) { if (obj.children[i].tagName == "UL") { var c = obj.children[i].children[0]; alert("child id is :-" + c.tagName); alert("child id is :-" + c.id); alert("child value is :-" + c.innerHTML); break; } } }

 #child { display: none; }

 <!DOCTYPE html> <html> <body> <div id="Parent" onmouseover="ok(this)">Find Child ? mouse over me <p id="child">I'm Child</p> <ul> <li id="list">hello</li> </ul> </div> </body> </html>

如何确定对象是否具有某些元素的子元素？

问题描述

2 个解决方案

解决方案1
0 2017-03-02 11:43:30

解决方案2
0 2017-03-02 11:53:12

如何确定对象是否具有某些元素的子元素？

问题描述

2 个解决方案

解决方案1 0 2017-03-02 11:43:30

解决方案2 0 2017-03-02 11:53:12

解决方案1
0 2017-03-02 11:43:30

解决方案2
0 2017-03-02 11:53:12