JavaScript implements the generation of 4-digit random verification code

This article example shares the specific code for JavaScript to generate a 4-digit random verification code for your reference. The specific content is as follows

Code:

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Generate 4-digit random verification code</title>
<style>
 label{
 color:aqua;
 float:left;
 font-size: 20px;
 line-height:2em;
 }
 #tex{
 display:inline-block;
 width:50px;
 height: 25px;
 float:left;
 text-align: center;
 font-size:15px;
 margin-top:10px;
 }
 #showyz{
 border:3px solid green;
 color:blue;
 width:90px;
 height:40px;
 text-align:center;
 float:left;
 margin-left:15px;
 line-height: 2.5em;
 
 }
 #hyz{
 background-color:burlywood;
 border:1px solid burlywood;
 width:50px;
 height:20px;
 float: left;
 margin-left:20px;
 margin-top: 10px;
 margin-right:15px;
 }
 #btn{
 
 }
</style>
</head>
<body>
<label for="tex">Please enter the verification code:</label><input type="text" id="tex" maxlength="4" autofocus>
<div id="showyz"></div>
<div id="hyz">Change one</div><br>
<input type="button" id="btn" value="Confirm">
</body>
<script>
//Define an empty array to save 62 codes var codes=[];
//Save the code corresponding to the number into the codes array, the digital code range is [48-57]
for(var i=48;i<=57;i++){
 codes.push(i);
}
//Save the codes corresponding to uppercase letters into the codes array, corresponding to the code range [65-90]
for(var i=65;i<=90;i++){
 codes.push(i);
}
//Save the codes corresponding to lowercase letters into the codes array, corresponding to the code range [97-122]
for(var i=97;i<=122;i++){
 codes.push(i);
}
//Define a method to generate a 62-bit random number as an array subscript, return a random code, and then convert the code into a corresponding number or letter function suiji(){
var arr=[]; //define an array to store 4-bit random numbers for(var i=0;i<4;i++){
 var index = Math.floor(Math.random()*(61-0+1)+0); //Generate a random number var char = String.fromCharCode(codes[index]); //Decode arr.push(char); //Store in array arr }
 return arr.join(""); //Convert the array to a string, separated by spaces, and return }
var yzm=suiji();//Call method to return the verification code to yzm//Get the above element var tex=document.getElementById("tex");
var showyz=document.getElementById("showyz");
var hyz = document.getElementById("hyz");
var btn = document.getElementById("btn");
//Write the verification code into the div with id showyzshowyz.innerHTML=yzm;
//Realize the function of changing the verification code hyz.onclick=function(){
 yzm=suiji();
 showyz.innerHTML=yzm;
}
//Verify the verification code you entered with the random verification code obtained btn.onclick=function(){
 var textvalue=tex.value;//Get the input value if(textvalue.toLowerCase()==yzm.toLowerCase()){//Convert all values to lowercase for comparison alert("Verification code input is correct!");
 yzm=suiji();
  showyz.innerHTML=yzm;
 tex.value="";
 }
 else{
 alert("Verification code input is wrong, please re-enter!");
 yzm=suiji();
  showyz.innerHTML=yzm;
 tex.value="";
 }
}
</script>
</html>

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