如何修改XHR

Question

我有一个XHR对象。当send（）方法被触发时，我想提供一个没有服务器的响应，任何网络操作。

 var origSend = xhr.send;
xhr.send = function () {      
        waitForFile(xhr, url).then(responseData=>{
           //ı wantto that responseData , send to xhr response
           //this responseData comes from anywhere(webrtc,fetch,filesystem,localstorage,......) 
         }); // side-effect
     FileRequests.next({url: url})
    //origSend.call(xhr, arguments)  //I don't want to call original send method
}

//等待响应的代码

xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status==200) {
    console.log(xhr.responseText);
}
}

Answer 1

我解决了。

      Object.defineProperty(xhr, 'readyState', {
            writable: true,
            configurable: true
        });
        Object.defineProperty(xhr, 'status', {
            writable: true,
            configurable: true
        });
        Object.defineProperty(xhr, 'statusText', {
            writable: true,
            configurable: true
        });
        Object.defineProperty(xhr, 'responseText', {
            writable: true,
            configurable: true
        });
        Object.defineProperty(xhr, 'responseType', {
            writable: true,
            configurable: true
        });
        Object.defineProperty(xhr, 'response', {
            writable: true,
            configurable: true
        });
        xhr.readyState = 4;
        xhr.status = 200;
        xhr.statusText = "OK";
        xhr.responseType = "blob";
        xhr.response = data.blob; // whatever you want 
        xhr.onreadystatechange();