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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