Home > Article > Web Front-end > How to determine whether a tag exists in jquery
Judgment method: 1. Use the element selector to select the specified tag element. The syntax "$("tag name")" will return a jQuery object containing the specified tag; 2. Use the length attribute to determine whether the jQuery object is Is empty, the syntax is "object.length!=0", if true is returned, it exists, otherwise it does not exist.
The operating environment of this tutorial: windows7 system, jquery3.2.1 version, Dell G3 computer.
jquery method to determine whether a tag exists
##1. Use the jQuery element selector to select the specified element tag
The jQuery element selector selects elements based on their name.$("标签名")For example,
$("p") is to select the
tag element.
2. Use the length attribute to determine whether the jQuery object is empty.
The length attribute can get the length of the jQuery object; then you can check whether the length is 0. Determine whether the object is empty.jQuery对象.length!=0
Implementation example: Determine whether the p element tag and span element tag exist
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <style> .siblings,.siblings *{ display: block; border: 2px solid lightgrey; color: lightgrey; padding: 5px; margin: 15px; } #border{ border: 2px solid pink; } </style> <script src="js/jquery-3.2.1.min.js"></script> <script type="text/javascript"> $(document).ready(function() { $("button").click(function() { var len1=$("p").length; var len2=$("span").length; if(len1!=0){ console.log("p元素存在") }else{ console.log("p元素不存在") } if(len2!=0){ console.log("span元素存在") }else{ console.log("span元素不存在") } }); }); </script> </head> <body> <div class="siblings">div元素 <p>p(p元素)</p> <h2>h2(h2元素)</h2> <h3>h3(h3元素)</h3> <p>p(p元素)</p> </div> <button>检查p元素和span元素是否存在</button> </body> </html>It can be seen that in the above example, the p element tag exists, but the span element tag does not exist. [Recommended learning:
jQuery video tutorial, web front-end video]
The above is the detailed content of How to determine whether a tag exists in jquery. For more information, please follow other related articles on the PHP Chinese website!