用ajax驗證碼驗證碼

Question

我正在使用本教程，http://www.crackajax.net/captchaform.php，並且遇到問題。表單或驗證碼都不會被驗證。這裏是我的表單代碼：

<form action="https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8" method="POST" name="contact" id="contact" onsubmit="return checkform(this);"> 

***form elements removed*** 

<!-- Start Captcha --> 
<img src="captcha.php" border="0"> 
<p>Enter Letters:<input type="text" name="code" value=""><p> 
<input type="submit" value="Submit Form" onclick="return checkform()"> 

這裏是我的腳本：

<script language="JavaScript"> 

     var url = 'captcheck.php?code='; 
     var captchaOK = 2; // 2 - not yet checked, 1 - correct, 0 - failed 

     function getHTTPObject() 
     { 
     try { 
     req = new XMLHttpRequest(); 
      } catch (err1) 
      { 
      try { 
      req = new ActiveXObject("Msxml12.XMLHTTP"); 
      } catch (err2) 
      { 
      try { 
      req = new ActiveXObject("Microsoft.XMLHTTP"); 
      } catch (err3) 
      { 
    req = false; 
      } 
      } 
    } 
     return req; 
    } 

     var http = getHTTPObject(); // We create the HTTP Object   

     function handleHttpResponse() { 
     if (http.readyState == 4) { 
      captchaOK = http.responseText; 
      if(captchaOK != 1) { 
       alert('The entered code was not correct. Please try again'); 
       document.contact.code.value=''; 
       document.contact.code.focus(); 
       return false; 
       } 
       document.contact.submit(); 
      } 
     } 

     function checkcode(thecode) { 
     http.open("GET", url + escape(thecode), true); 
     http.onreadystatechange = handleHttpResponse; 
     http.send(null); 
     } 

     function checkform() { 
     // First the normal form validation 
     if(document.contact.req.value=='') { 
      alert('Please complete the "required" field'); 
      document.contact.req.focus(); 
      return false; 
      } 
     if(document.contact.code.value=='') { 
      alert('Please enter the string from the displayed image'); 
      document.contact.code.value=''; 
      document.contact.code.focus(); 
      return false; 
      } 
      // Now the Ajax CAPTCHA validation 
      checkcode(document.contact.code.value); 
      return false; 
     }  
</script> 

最後但並非最不重要的，這裏是captcha.php文件：

<?php 
//Start a session so we can store the captcha code as a session variable. 
session_start(); 
// Decide what characters are allowed in our string 
// Our captcha will be case-insensitive, and we avoid some 
// characters like 'O' and 'l' that could confuse users 
$charlist = '23456789ABCDEFGHJKMNPQRSTVWXYZ'; 

// Trim string to desired number of characters - 5, say 
$chars = 5; 
$i = 0; 
while ($i < $chars) 
{ 
    $string .= substr($charlist, mt_rand(0, strlen($charlist)-1), 1); 
    $i++; 
} 

// Create a GD image from our background image file 
$captcha = imagecreatefrompng('captcha.png'); 

// Set the colour for our text string 
// This is chosen to be hard for machines to read against the background, but 
// OK for humans 
$col = imagecolorallocate($captcha, 240, 200, 240); 

// Write the string on to the image using TTF fonts 
imagettftext($captcha, 17, 0, 13, 22, $col, 'Carton-Slab.otf', $string); 

// Store the random string in a session variable 
$_SESSION['secret_string'] = $string; 

// Put out the image to the page 
header("Content-type: image/png"); 
imagepng($captcha); 
?> 

的應用驗證碼圖像框會顯示出來，字母/數字也會顯示出來，但正如我前面提到的，表單/ captacha不會被驗證。表單提交後，用戶將被帶到感謝頁面。

Answer 1

我複製了教程中的代碼，它的工作原理。你沒有說關於captcheck.php文件的任何內容，它是否存在？使用本教程的captcheck.php和你的代碼 ，我不得不刪除

if(document.contact.req.value=='') { 
    alert('Please complete the "required" field'); 
    document.contact.req.focus(); 
    return false; 
} 

才能正常工作。