Examine source code of SubmitToBlank

{
  "manifest_version": 2,
  "name": "SubmitToBlank",
  "version": "1.1resigned1",
  "description": "Enable submitting forms to a new window/tab.\n\nThis is a simplified respin of the TabSubmit extension (which in turn is a rewrite of the SubmitToTab extension) done as a webextension for better forwardwards compatibility.\n\nThe current implementation works by setting the form target to '_blank'. This means it will open the form as a new window or tab. This behaviour is controlled using the general Firefox preferences.",
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "submit-to-blank.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9de6267a-72d0-4e22-8258-d1b9ed816e9e}"
    }
  }
}