编写XHR请求处理库时遇Uncaught TypeError，求解决方法

Hey there! Let's break down what's happening here and how to fix this frustrating issue.

First, Let's Decode the Error #

Look closely at the error stack you shared:

Uncaught TypeError: ns.GetCommandSrc is not a function
at GetCommandUrl (main.js?attr=7N7be5KFTB_XK1v3646uVIL17y569qG6DwMTgbv_iXZvqSna9AM-9MNlqFPvJklSwn76uz-fcLWPIOcuFrAZuA:988)
at XMLHttpRequest.window.XMLHttpRequest.open (main.js?attr=...)
at easyHTTP.post (easy.js:13)
at newapp.js:23

The key detail here is that the error originates in a main.js file that's not part of your codebase (your files are easy.js and newapp.js). Your code isn't the direct cause of this problem—something else is messing with native browser functionality.

Likely Root Cause: External Script/Extension Tampering #

This error almost always means a third-party script (like a browser extension, or injected code on the page) has modified the native XMLHttpRequest.open method. When your code calls this.http.open(), it's running the broken, modified version from that external main.js instead of the browser's original method.

Step-by-Step Fixes #

1. Rule Out Browser Extension Interference #

• Run your page in Incognito/Private Mode—most browsers disable extensions by default here. If the error disappears, you know a browser extension is the culprit.
• To find which one: Go back to normal mode, disable all extensions, then re-enable them one by one until the error comes back. That's the extension causing the trouble.

2. Check for Injected Third-Party Scripts #

• Open your browser's DevTools (F12), go to the Sources tab. Locate the main.js?attr=... file, right-click it and select "Copy link address" to see where it's coming from. If it's not hosted on your server, it's injected code from an external source.

3. Workaround: Use the Native XMLHttpRequest #

If you can't remove the interfering script immediately, bypass the modified XMLHttpRequest by saving the native version before your code runs:

// Add this at the VERY TOP of easy.js
const NativeXHR = window.XMLHttpRequest;

function easyHTTP() { 
  // Use the saved native constructor instead of the modified one
  this.http = new NativeXHR(); 
}

// Rest of your post method (with improved error handling)
easyHTTP.prototype.post = function (url, data, callback) {
  this.http.open('POST', url, true);
  this.http.setRequestHeader('Content-type', 'application/json');
  let self = this;
  
  // Add proper success/error handling (your original code missed this!)
  this.http.onload = function () {
    if (self.http.status >= 200 && self.http.status < 300) {
      callback(null, self.http.responseText);
    } else {
      callback(new Error(`Request failed with status: ${self.http.status}`), null);
    }
  };
  
  // Handle network errors like no internet connection
  this.http.onerror = function () {
    callback(new Error('Network connection failed'), null);
  };
  
  this.http.send(JSON.stringify(data));
}

4. Improve Your Error Handling (Bonus) #

Your original code didn't account for HTTP error statuses (like 404 or 500) or network failures. The modified code above adds this, so you'll get meaningful feedback when something goes wrong with the actual request.

内容的提问来源于stack exchange，提问作者Dijiflex