How to Solve 'Cannot Read Property of Undefined' Errors When Using Chrome APIs in Content Scripts?

"Cannot Read Property of Undefined" Error with Chrome APIs in Content Scripts

Chrome extensions often use content scripts to inject JavaScript into web pages. One common issue arises when trying to access chrome APIs, such as chrome.tabs, within these content scripts.

The error "Cannot read property 'name' of undefined" indicates that the API is not available in the content script context. This is because content scripts have limited access to chrome APIs compared to other script types like background scripts and popup scripts.

Cause:

Content scripts are sandboxed and only have access to a specific set of APIs, including chrome.i18n, chrome.dom, chrome.storage, and a subset of chrome.runtime/chrome.extension.

Solution:

To access restricted chrome APIs like chrome.tabs in a content script, you can use message passing to communicate with a suitable script type (e.g., background script).

Implementation:

1. Pass a message from the content script to a background script, popup script, or service worker (for MV3).

// In contentScript.js
chrome.runtime.sendMessage({ action: "getTabs" });

2. Handle the message in the recipient script.

// In backgroundScript.js
chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  if (request.action === "getTabs") {
    chrome.tabs.query({}, (tabs) => {
      sendResponse(tabs);
    });
  }
});

3. Use the API in the appropriate script and return the result to the content script.

By following these steps, you can use chrome APIs that are unavailable in content scripts by delegating the requests to more privileged script types through message passing.

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