[英]Modiying request headers in an XMLHttpRequest
I've made an ajax call interceptor to listen for XMLHttpRequests. 我已经制作了一个ajax调用拦截器来监听XMLHttpRequests。
I would like to modify the request headers of the XHR. 我想修改XHR的请求标头。 For some reason I can only change them in XMLHttpRequest.send()
. 出于某种原因,我只能在XMLHttpRequest.send()
更改它们。 Is it to early to modify them in XMLHttpRequest.open()
? 是否要在XMLHttpRequest.open()
修改它们? It throws the exception that I pasted in the code below. 它抛出了我粘贴在下面的代码中的异常。
So, why do I get an error? 那么,为什么我会收到错误?
(function (open) {
XMLHttpRequest.prototype.open = function () {
this.setRequestHeader('foo', 'bar');
// InvalidStateError: An attempt was made to
// use an object that is not, or is no longer, usable
open.apply(this, arguments);
};
})(XMLHttpRequest.prototype.open);
(function (send) {
XMLHttpRequest.prototype.send = function () {
this.setRequestHeader('foo', 'bar'); // OK
send.apply(this, arguments);
};
})(XMLHttpRequest.prototype.send);
for(var i = 0; i < 3; i++){
var rnd = Math.round(Math.random()*3+1),
httpRequest = new XMLHttpRequest();
httpRequest.onreadystatechange = function () { };
httpRequest.open('GET', '/echo/json?delay=' + rnd);
httpRequest.send();
}
What if you swap: 如果你交换怎么办:
this.setRequestHeader('foo', 'bar');
open.apply(this, arguments);
to get: 要得到:
open.apply(this, arguments);
this.setRequestHeader('foo', 'bar');
does it work then? 它有效吗?
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