为什么在调用 open throw 之前设置 XMLHttpRequest responseType?

2022-01-15 00:00:00 xmlhttprequest javascript ajax specifications w3c

在控制台中运行 new XMLHttpRequest().responseType = "json" 会在 Firefox 26 和 IE11 中引发InvalidStateError"异常，但在 Chrome 31 中不会.

Running new XMLHttpRequest().responseType = "json" in the console throws an "InvalidStateError" exception in Firefox 26 and IE11 but not in Chrome 31.

为什么?

规范声明设置 responseType

如果状态为 LOADING 或 DONE，则抛出InvalidStateError"异常.

throws an "InvalidStateError" exception if the state is LOADING or DONE.

但在这种情况下，状态是 UNSENT.

but in this case the state is UNSENT.

发生了什么事?

推荐答案

这是一个工作草案，所以如果在实现中存在小的差异或错误是正常的.我认为 Firefox 仍然遵循 2011 年 8 月草案中描述的行为，其中指定抛出异常如果状态不是 OPENED 或 HEADERS_RECEIVED.

It's a working draft, so it's normal if there are small differences or bugs in the implementations. I think Firefox still follows the behavior described in the draft of August 2011, where is specified that the exception is thrown if the state is not OPENED or HEADERS_RECEIVED.

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