XMLHttpRequest状态码始终为0

Question

I am trying to operate on all ajax requests and specifically handle 409s, but my status code is always 0 even though FireFox debugger will clearly show me a 409.

JS Code

(function(open) {
  XMLHttpRequest.prototype.open = function(method, url, async, user, pass) {
    if(this.status === 409)
        console.log("Conflict 409")
    open.apply(this, arguments);
  };
})(XMLHttpRequest.prototype.open);

I can extremely easily generate 409s with my server code. I see FireFox and Chrome showing 409s. But this.status is always 0, even on 400s. What am I doing wrong?

Answer 1

You're checking status before the request has finished.

You can use xhook library to intercept XHR responses.

Example:

xhook.after((request, response) => {
  if (response.status === 409) {
    console.log("Conflict 409")
  }
})