Optionally inject Content Script

Question

Content Script can be injected programatically or permanently by declaring in Extension manifest file. Programatic injection require host permission, which is generally gran

Answer 1

Since the existing answer is now a few years old, optional injection is now much easier and is described here. It says that to inject a new file conditionally, you can use the following code:

// The lines I have commented are in the documentation, but the uncommented
// lines are the important part

//chrome.runtime.onMessage.addListener((message, callback) => {
//   if (message == “runContentScript”){

        chrome.tabs.executeScript({
          file: 'contentScript.js'
        });

//   }
//});

You will need the Active Tab Permission to do this.