（AJAX / PHP）在这个简短的示例中，为什么我的POST请求不起作用？

Question

Here is my JavaScript:

var xhr = new XMLHttpRequest();
xhr.open("POST", "pants.php", true);
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4) {
        var slot = document.getElementsByTagName("section")[0].innerHTML = xhr.responseText;
    }
}
xhr.send("name=Sarah");

I am sending "name=Sarah" to testpage.php via POST, and when I get a response, I'm doing to display it on my page.

And here's pants.php:

echo $_POST['name'];

So I should just be displaying "Sarah" on the page. But instead, I get the error ": Undefined index: name". I can't seem to understand why this is...

Answer 1

You should add the following:

xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')

This header is mandatory for POST requests