InjectionMV3

Chrome Extension to inject JS into the main page context with Manifest Version 3

In MV3, it's no longer possible to ... TODO

CSP solution

Create injection script:

// Should be accessible in the main page context
// This is not normally the case with content scripts
window.testVariable = true;

Add script to web_accessible_resources section of manifest.json

Link injection script into src property of script like so:

const script = this.document.createElement('script')
script.src = chrome.runtime.getURL("injection.js")
this.document.documentElement.appendChild(script)

// clean it up afterwards
this.document.documentElement.removeChild(script)

To get the url of the script from the extension resources:

chrome.runtime.getURL("injection.js")