XMLHttpRequest没有返回值

Question

我无法收到来自php文件的响应。

Java脚本

var http = new XMLHttpRequest();
var url = "http://localhost/php_bollywood_romance.php";
var params = "film="+movie_name_entered;
http.open("POST", url, true);
//Send the proper header information along with the request
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");

http.onreadystatechange = function() {//Call a function when the state changes.
    if(http.readyState == 4 && http.status == 200) {
        alert(http.responseText);
    }
}
http.send(params);

我什至试图做到这一点.....

 var http = new XMLHttpRequest();
 if ("withCredentials" in http)
 {
    var url = "http://localhost/php_bollywood_romance.php";
var movie_name_entered="hi";
var params = "film="+movie_name_entered;
http.open("POST", url, true);
 }
 else if (typeof XDomainRequest != "undefined"){
    http = new XDomainRequest();
    var url = "http://localhost/php_bollywood_romance.php";
    var movie_name_entered="hi";
    var params = "film="+movie_name_entered;
    http.open("POST", url);
} else {
    http = null;
}
if (http){
http.onload = function(){
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");

http.onreadystatechange = function() {//Call a function when the state changes.
    if(http.readyState == 4 && http.status == 200) {
        document.write(http.responseText);
        callback(http.responseText);
        alert("hey");
    }
}
http.send(params);
};

的PHP

  <?php
    {
     $name = $_POST["film"];
      $file ='data_bollywood_romance.txt';
       $current=file_get_contents($file); //gets existing content from the file
    $current ="$current \n $name \n";
   file_put_contents($file,$current); //put newstuff
    echo 'hi';
   return 'yes';
     }
   ?>

但是，这似乎也行不通...如果我在http.send（params）之后执行alert（“ http.response”）...它会在没有写任何内容的情况下发出警报。 我认为这可能是因为存在相同的源策略问题，所以我尝试使用跨域资源共享来进行跨域Ajax，但是这也不起作用（这是第二个代码）。 感谢您的帮助。

Answer 1

您不能设置这两个标题：

http.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");

有关您的问题的上一个主题

我尝试了一下，但效果很好。

就个人而言，我将使用jQuery Ajax进行所有操作，但这就是“懒惰的我” :)