How to create an chrome extension
1. See the useless official document
https://developer.chrome.com/extensions/getstarted
2. See my codes
https://github.com/yingshaoxo/No_More_Chinese/tree/example-of-chrome-extension
3. Core question
+ [Content scripts](https://developer.chrome.com/extensions/content_scripts) have only limited access to Chrome APIs. This access does not include the API you are trying to use (e.g. `chrome.tabs`). If you need to use that API, you will have to do so in a [background script](https://developer.chrome.com/extensions/background_pages).
https://developer.chrome.com/extensions/getstarted
2. See my codes
https://github.com/yingshaoxo/No_More_Chinese/tree/example-of-chrome-extension
3. Core question
+ [Content scripts](https://developer.chrome.com/extensions/content_scripts) have only limited access to Chrome APIs. This access does not include the API you are trying to use (e.g. `chrome.tabs`). If you need to use that API, you will have to do so in a [background script](https://developer.chrome.com/extensions/background_pages).