How to determine whether the element content is empty in jquery

Jquery method to determine whether the element content is empty: 1. Use the [if(value.length == 0){}] method to perform the operation if the value is empty; 2. Use [if(value! =''){}] method, the operation performed if value is not empty.

The operating environment of this tutorial: windows7 system, jquery3.2.1 version. This method is suitable for all brands of computers.

Jquery method to determine whether the element content is empty:

input uses val();

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

How to judge whether it is empty:

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

• if(value!=''){}Executed if value is not empty Operation

jQuery validates that the text box content is not empty

Extended jQuery method by

$.fn

/**
 * 校验文本是否为空
 * tips：提示信息
 * 使用方法：$("#id").validate("提示文本");
 * @itmyhome
 */
$.fn.validate = function(tips){
 
  if($(this).val() == "" || $.trim($(this).val()).length == 0){
    alert(tips + "不能为空！");
    throw SyntaxError(); //如果验证不通过，则不执行后面
  }
}

html element uses html();

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

How to judge whether it is empty:

if(value.length == 0){

You can also judge whether there are any 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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<li><a href="https://m.jb51.net/game/80896.html"><img src="//img.jbzj.com/do/uploads/litimg/130503/1J21Va46.jpg">完美女友完整版</a><em class="xj star5"></em></li>
</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() === "" ){} 用三个等号更符合

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