哪些 HTTP 状态代码会在 XMLHttpRequest 上触发错误事件

Question

I've read every spec I can find, even the W3 for ProgressEvents as well as XMLHttpRequest , and I'm finding diddly regarding WHICH status codes (or What response) fire an Error event on an async XHR request. The most I can find is references to checking the status code itself on the object and handling that, which normally treats anything but 200 as an Error, yet a 3xx redirect from, say, a POST is not an Error (I can't recall if the XHR will follow a redirect automatically) Can someone help me out or point me in the right direction regarding the spec (no libraries) for all responses that initiate an onerror event?

Answer 1

onerror only fires for network-level events, which means that onload will fire if there is a successful response, regardless of HTTP status code. See this question for more discussion: When should XMLHttpRequest's onerror handler fire