JSFiddle Auto Run & Save

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "JSFiddle Auto Run & Save",
  "description": "This extension makes JSFiddle automatically run & save while typing, also adds a button to hide panels other than js",
  "version": "0.0.1",
  "icons": {
    "16": "images/icon-enabled-16.png",
    "48": "images/icon-enabled-48.png",
    "128": "images/icon-enabled-128.png"
  },
  "background": {
    "scripts": [
      "scripts/background.js"
    ],
    "persistent": false
  },
  "page_action": {},
  "content_scripts": [
    {
      "matches": [
        "https://jsfiddle.net/*"
      ],
      "js": [
        "scripts/jsfiddle-mixin.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "tabs",
    "storage",
    "declarativeContent"
  ]
}