Chrome Plugins 101

1. Print innerHTML every 3 seconds

manifest.json

{
  "manifest_version": 2,

  "name": "Try me",

  "version": "0.3",

  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [{

    "js": [ "content-script.js" ],

    "all_frames": true,

    "run_at": "document_end",

    "matches": ["<all_urls>"]

  }]

}

content-script.js

window.setInterval(function() {

  alert(document.getElementsByTagName('html')[0].innerHTML);

}, 3000);