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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> <title>JavaScript 验证码</title> <script type="text/javascript" > var code = ""; //验证码 //生成验证码 function createCode(){ var num = 4; //验证码位数 var codeList = new Array(1,2,3,4,5,6,7,8,9,0,'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'); //验证码内容 //循环获取每一位验证码 for(var i = 0; i < num; i++){ //随机数 * 验证码候选元素数量 = 候选元素数组下标 code += codeList[Math.floor(Math.random() * codeList.length)]; } document.getElementById("txtCode").value = code; } //校验用户输入的验证码是否正确 function checkCode(){ if(document.getElementById("inputCode").value == code) alert("验证码输入正确!"); else alert("验证码填写错误!"); code = ""; createCode(); //生成新的验证码 } </script> </head> <body onload="createCode()"> 请输入验证码:<input id="inputCode" type="text" /><input id="txtCode" type="text" readonly /><input name="btnCheck" type="button" value="验证" onclick="checkCode()" /> </body> </html>