javascript - Function.prototype.apply.apply - 为什么调用它两次

Question

今天在检查Jasmine 的源代码时here我偶然发现了以下内容:

if (queueableFn.timeout) {
    timeoutId = Function.prototype.apply.apply(self.timeout.setTimeout, [j$.getGlobal(), [function() {
      var error = new Error('Timeout - Async callback was not invoked within timeout specified by jasmine.DEFAULT_TIMEOUT_INTERVAL.');
      onException(error);
      next();
    }, queueableFn.timeout()]]);
}

我感兴趣的是为什么apply在这里被调用了两次prototype.apply.apply

Answer 1

commit that introduced this syntax解释一切:

Older IE fixes Still not green, but getting close. Summary of Older IE discrepancies:

• Older IE doesn't have apply/call on the timing functions
• Older IE doesn't allow applying falsy arguments
• Older IE doesn't allow setting onclick to undefined values
• Older IE doesn't have text property on dom nodes