jQuery ajax请求在控制台中成功，但未调用回调

Question

I have a jQuery POST request that looks something like this:

$.ajax("/myurl",{
    data:{
        ...
    },
    mimeType:"application/json",
    dataType:"application/json",
    method:"POST",
    success:function(r){
        console.log("success");
    },
    error:function(r){
        console.log("error");
        console.log(r);
    }
});

I turned on XHR logging in my chrome console, and it says the XHR finished loading: POST http://localhost/myurl . However, "error" is logged in my console as well, along with an XHR object:

error
{readyState: 4, getResponseHeader: ƒ, getAllResponseHeaders: ƒ, setRequestHeader: ƒ, overrideMimeType: ƒ, …}
XHR finished loading: POST "http://localhost/myurl"

Why is it saying that the XHR finished loading, but at the same time there's an error? Why is there even an error? On the server-side, the server receives the request and sends a response.

Answer 1

The most likely explanation is that what the server is sending back isn't valid JSON, so although the ajax succeeds, parsing the JSON fails.

Your dataType is off, though, it should have one of these values: "xml" , "json" , "script" , or "html" — in your case, "json" . You also don't need (and probably don't want) to set mimeType .