如何在400个错误请求后返回JSON数据

HTTP 400 Bad Request
Allow: POST, OPTIONS
Content-Type: application/json
Vary: Accept
{
    "username": [
        "Username already taken."
    ],
    "email": [
        "This field may not be blank."
    ],
    "password1": [
        "This field may not be blank."
    ],
    "password2": [
        "This field may not be blank."
    ]
}

console.log(send_data(register_url, data));

function send_data(url, data) {
    return $.ajax({
        url: url,
        type: 'POST',
        data: data,
        success: function (data) {
        },

        error: function (xhr) {
        }
    });
}

当我调用函数时,我会检索所有数据。像这样:

abort: ƒ (e)
always: ƒ ()
catch: ƒ (e)
done: ƒ ()
fail: ƒ ()
getAllResponseHeaders: ƒ ()
getResponseHeader: ƒ (e)
overrideMimeType: ƒ (e)
pipe: ƒ ()
progress: ƒ ()
promise: ƒ (e)
readyState: 4
responseJSON: {email: Array(1), password1: Array(1), password2: Array(1)}
responseText: "{"email":["This field is required."],"password1":["This field is required."],"password2":["This field is required."]}"
setRequestHeader: ƒ (e,t)
state: ƒ ()
status: 400
statusCode: ƒ (e)
statusText: "Bad Request"
then: ƒ (t,r,i)
__proto__: Object

但是,当我这样做时:

let resp = send_data(register_url, data);
console.log(resp.responseJSON);

我明白了 undefined