How do I send an HTTP GET request from a Chrome extension?

Question

I'm working on a chrome extension that sends a HTTP request using the method GET.

How do I send a GET to www.example.com with the parameter par with value 0?

https://www.example.com?par=0 

(the server reads the parameter par and does something)

I found this article, talking about Cross-Origin XMLHttpRequest, but I don't know how their example could help me.

Answer 1

First, you'll need to edit your manifest.json and add the permission for www.example.com:

• For the new Manifest V3, use the host_permissions field:

  {     "manifest_version": 3,     ...     "host_permissions": [         "https://www.example.com/*"     ],     ... } 

• If you are still using the old Manifest V2, use the permissions field:

  {     "manifest_version": 2,     ...     "permissions": [         "https://www.example.com/*"     ],     ... } 

Then in your background page (or somewhere else) you can do:

fetch('http://www.example.com?par=0').then(r => r.text()).then(result => {     // Result now contains the response text, do what you want... }) 

See also MDN doc for fetch().

---

Deprecated version using XMLHttpRequest (ES5):

function callback() {     if (xhr.readyState === XMLHttpRequest.DONE) {         if (xhr.status === 200) {             result = xhr.responseText;             // ...         }     } };  var xhr = new XMLHttpRequest(); xhr.open("GET", "http://www.example.com?par=0", true); xhr.onreadystatechange = callback; xhr.send(); 

NOTE the warning at the top of the relative documentation page:

In Manifest V3, XMLHttpRequest is not supported in background pages (provided by Service Workers). Please consider using its modern replacement, fetch()