Examine source code of Character Input

{
  "manifest_version": 2,
  "name": "Character Input",
  "version": "3.2",
  "author": "Thomas Meehan (Orangeaurochs)",
  "description": "Press Insert key, then enter a character code: aXXX or aXXXX for an Alt Code, uXXXX or XXXX for a Unicode code, c for a copyright symbol. Accepts CP437 and CP1252 Alt Codes, not CP850. Designed for Ex Libris Alma. Version 3 of Unicode Input.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "js": [
        "character_input.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{98da0ed0-76c4-43ab-9754-82ce89ae5f50}"
    }
  }
}