jquery determines whether element content exists-JS Tutorial-php.cn

jquery determines whether element content exists

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Release： 2018-05-14 11:17:42

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This time I will bring you jquery to determine whether the element content exists. What are the precautions for jquery to determine whether the element content exists? The following is a practical case, let's take a look.

Input uses val();

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

Judge whether it is empty Method:

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

if(value!=''){} Operations performed if value is not null

jQuery verifies that the content of the text box is not empty

Extended jQuery method through $.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
  }
}

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html elementUse 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 the method of html acquisition,

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

Method 1

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

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Method 2,

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

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if( $("#list").html() === "" ){} Use three etc. The number is more in line with

. I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!