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Javascript method to determine whether the id exists: 1. Create an HTML sample file; 2. Add a script tag; 3. Use the "function exist(id){...}" method to determine whether the id exists. .
The operating environment of this article: windows7 system, javascript version 1.8.5, Dell G3 computer.
How does JavaScript determine whether the id exists?
js method to determine whether id exists
The code is as follows:
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Document</title> <script type="text/javascript"> // window.onload=function(){ // alert(exist("getSpanText")); // alert(exist("111")) // } function loadText(){ alert(exist("getSpanText")); } function exist(id){ var s=document.getElementById(id); if(s){ return true } else{ return false } } </script> </head> <body onload="loadText()"> <span id="getSpanText">Jason</span》 </body> </html>
[Recommended learning: javascript basic tutorial]
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