Answers for "how to use manifest in chrome"

manifest chrome extension

//manifest.json
{
  "name": "My chrome extension",
  "version": "1.0",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["./src/content.js"]
    }
  ]
}

chrome manifest

{
  "name": "Getting Started Example",
  "description": "Build an Extension!",
  "version": "1.0",
  "manifest_version": 3
}