一、js：

1. 要点：
   
2. 完整代码：

   <script>
   if(window.XMLHttpRequest){  // code for IE7+, Firefox, Chrome, Opera, Safari
       xmlhttp=new XMLHttpRequest();
   }else{  // code for IE6, IE5
       xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
   }
   xmlhttp.onreadystatechange = function(){
       console.log(xmlhttp.readyState)
       if(xmlhttp.readyState < 4){
           console.log('loading...')
       }else if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
           xmlDoc=xmlhttp.responseText;
           console.log(xmlDoc)
       }else{
           console.log('fail...')
           xmlhttp.abort()
       }
   }
   xmlhttp.open("POST",'test.php',true,'user','pwd');
   xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
   xmlhttp.setRequestHeader('name', 'lee');
   xmlhttp.send(null);
   </script>

   二、php：

3. 要点：
   
4. 完整代码：

   <?php
   header('Access-Control-Allow-Origin:*');
   header('Access-Control-Allow-Credentials: true');
   header('Access-Control-Allow-Methods:GET,PUT,POST,DELETE,OPTIONS');
   header('Access-Control-Allow-Headers:WWW-Authenticate,Authorization,Set-Cookie,X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version,name');
   $header = apache_request_headers();
   var_Dump($header['name']);exit;