How to verify if an element is empty in jquery

Jquery method to verify whether an element is empty: 1. Use [val()] to judge input, and the code is [var value = $('#test').val()]; 2. Use [html ()] Judgment, the code is [var value = $('#test').html()].

The operating environment of this tutorial: windows10, jquery2.2.4, this article is applicable to all brands of computers.

Jquery method to verify whether an element is empty:

Input uses val();

var value = $('#test').val();

Whether it is empty Judgment method:

• if(value.length == 0){} Operation performed if value is empty

• if(value!= ''){} If the value is not empty, the operation performed

html element is judged by html();

var value = $('#test').html();

is empty. Method:

if(value.length == 0){

You can also judge whether there are child nodes? For html acquisition methods, you can use

$('#list').children().length === 0

Method 1

<script type="text/javascript" src="http://m.jb51.net/skin/mobile/js/jquery.min.js"></script>
<div><ul id="thelist2">
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</ul>
<div><ul id="thelist3"></ul>
<script>
alert($(&#39;#thelist2&#39;).children().length)
alert($(&#39;#thelist3&#39;).children().length)
$thelist3 = $(&#39;#thelist3&#39;);
if($thelist3.children().length==0){
//插入广告
}
/*
thel3con = $(&#39;#thelist3&#39;).html();
alert(thel3con.length);
if(thel3con=""){
alert("空");
 
}else{
alert("非空");
}
*/
</script>

Method 2,

String.prototype.isEmpty = function () {
 var s1 = this.replace(/[\r\n]/g, '').replace(/[ ]/g, ''),
   s2 = (s1 == '') ? true : false;
 return s2;
};
$list.html().isEmpty();

if( $("#list").html() === "" ){} Using three equal signs is more in line with

Related free learning recommendations: JavaScript (video)

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