<script language="javascript">var code; //在全局 定義驗(yàn)證碼function createCode(){ //創(chuàng)建驗(yàn)證碼函數(shù) code = ""; var codeLength =4;//驗(yàn)證碼的長(zhǎng)度 var selectChar = new Array(0,1,2,3,4,5,6,7,8,9,'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');//所有候選組成驗(yàn)證碼的字符，當(dāng)然也可以用中文的 for(var i=0;i<codeLength;i++) {  var charIndex =Math.floor(Math.random()*36); code +=selectChar[charIndex];  }// 設(shè)置驗(yàn)證碼的顯示樣式，并顯示 document.getElementById("discode").style.fontFamily="Fixedsys"; //設(shè)置字體 document.getElementById("discode").style.letterSpacing="5px"; //字體間距 document.getElementById("discode").style.color="#0ab000"; //字體顏色 document.getElementById("discode").innerHTML=code; // 顯示}function but(){//驗(yàn)證驗(yàn)證碼輸入是否正確 var val1=document.getElementById("t1").value; var val2=code; if(val1!=val2){  alert("驗(yàn)證碼錯(cuò)誤!"); document.getElementById('t1').value="";  } }</script>

 <div class="input">    <input id="t1" type="text" name="u" placeholder="驗(yàn)證碼" onblur="but()" />    <span id="discode"></span>    <input type="button" value="換一換" class="c" style="height:20px;"onClick="createCode()">    </div>