通过不带jQuery的AJAX从JavaScript到PHP的POST值 [英] POST value from JavaScript to PHP via AJAX without jQuery

问题描述

我正在尝试发送一个JavaScript变量，以供PHP在服务器端进行处理，然后回显结果.我的ajax请求结果为readyState == 4和status == 200，但是PHP一直在回显一个空数组/值.

I'm trying to send a JavaScript variable to be processed server-side by PHP then echo back the result. My ajax request results in readyState == 4 and status == 200 yet PHP keeps echoing back an empty array/value.

我很确定这来自我的Ajax调用，该请求发送了一个空请求，但是我尝试的所有操作均不起作用，所以也许我在这里出错了.

I'm pretty sure this comes from my Ajax call sending an empty request but everything I tried didn't work, so maybe I'm going all wrong here.

JS(来自index.html):

var valueToSend = Math.random(); 

var request = false;
if (window.XMLHttpRequest) {
    request = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
    request = new ActiveXObject('Microsoft.XMLHTTP');
}

function send_ajax() {
    if (request) {
        request.open('POST', 'test.php', true);
        request.onreadystatechange = function() {
            if (request.readyState == 4 && request.status == 200) {
                console.log(request.responseText);
            }
        }
        request.send(valueToSend); //this line is probably not sending the value the way I expect it to
    }
}

PHP(来自test.php):

echo $_POST['name']; //simple echo to check if PHP indeed receives valueToSend

我的最后一次尝试是用.send(encodeURI('name=' + valueToSend));更改request.send(valueToSend);，但是它只是使ajax调用将页面位置重定向到一个不存在的页面.

My last try was to change request.send(valueToSend); with .send(encodeURI('name=' + valueToSend)); but it just made the ajax call redirect the page location to a non-existing one.

我在做什么错了?

推荐答案

您的代码中几乎没有错误，例如:

There are few things wrong in your code, such as:

• 即使通过定义的send_ajax()函数，您也没有在代码中的任何地方调用它.

• 使用POST请求，您需要将HTTP标头setRequestHeader()与请求一起发送，如下所示:

• Even through you defined send_ajax() function, you didn't call it anywhere in the code.

• With POST request you need to send an HTTP header setRequestHeader() along with the request, like this:

request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

test.php 页面中的

echo $_POST['name'];无法使用，因为此处name是 undefined .您的send()方法调用应如下所示:

echo $_POST['name']; in test.php page won't work because name is undefined here. Your send() method call should be like this:

request.send("name="+valueToSend);

因此完整的JavaScript代码如下:

So the complete JavaScript code would be like this:

var valueToSend = Math.random(); 

var request = false;
if (window.XMLHttpRequest) {
    request = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
    request = new ActiveXObject('Microsoft.XMLHTTP');
}

function send_ajax() {
    if (request) {
        request.open('POST', 'test.php', true);
        request.onreadystatechange = function() {
            if (request.readyState == 4 && request.status == 200) {
                console.log(request.responseText);
            }
        }
        request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        request.send("name="+valueToSend);
    }
}

send_ajax();

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