服务器未看到JavaScript Ajax请求中发送的JSON

Question

I'm trying to make an ajax request in straight javascript (jQuery is not available to me) with some JSON parameters. The javascript:

var params = {'ajax': true, 'albumid': albumid, 'sequencenum': sequencenum};
var xhr = new XMLHttpRequest();
xhr.onreadystatechange=function()
{
    if (xhr.readyState==4 && xhr.status==200)
    {
        console.log(xhr.responseText);
    }
}
xhr.open("GET","viewpicture.php",true);
xhr.setRequestHeader("Content-Type", "application/json")
console.log("sending request");
xhr.send(JSON.stringify(params));

In viewpicture.php, a var_dump($_GET) yields an empty array. What am I doing wrong?

Answer 1

In short, when you make a GET request, .send is expected to have 0 params (or be null ). The only way to send the data through GET would be to append it to the URL itself.

To wit:
If you were sending in form-data, in a POST , the anticipation would be that send would contain the form-encoded data (json for json-data, etc), and the URL would just be the access point on the server.

A GET request is just fetching data from that access point (including query string).
See where I'm going with this?

So if you want this to work in a GET , you need to set your JSON as a property of a query parameter (or turn it into query params/values).

Answer 2

If you want to send in the request body you should use a POST request, however if you need to use a get request you should send the data as key value pairs in the url. eg xhr.open("GET","viewpicture.php?data=" + encodeURIComponent(JSON.stringify(params)),true); Then retrieve via $_GET['data'] .