How to fix chrome-extension inline JavaScript invocation error?

Question

I'm making a chrome extension however I seem to get the following error when I try to fire up an onclick() event.

Refused to load the script 'https://apis.google.com/js/client.js?onload=handleClientLoad' because it violates the following Content Security Policy directive: "script-src 'self' blob: filesystem: chrome-extension-resource:"

and

Refused to execute inline event handler because it violates the following Content Security Policy directive: "script-src 'self' blob: filesystem: chrome-extension-resource:". Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution.

This is my manifest.json :

{
  "manifest_version": 2,

  "name": "SECURE",
  "description": "this extension offers secure communication for GMAIL     users",
  "version": "1.0",

 "browser_action": {
 "default_icon": "resources/icon16.png",
 "default_popup": "popup.html",
 "default_title": "Click here!"


 },

 "background":{
   "scripts":["background.js"]
},

 "content_scripts": [
  {
   "matches": ["http://*/*", "https://*/*"],
   "js":["myscript.js"],
   "run_at": "document_end"
  }
  ],
"permissions": ["identity", "https://accounts.google.com/*",  "https://www.googleapis.com/*"],

"oauth2": {
   "client_id": "975410329966.apps.googleusercontent.com",
 "scopes": [
   "<all urls>",
   "https://www.googleapis.com/auth/drive",
   "https://mail.google.com/",
   "https://www.googleapis.com/auth/gmail.login",
   "https://www.googleapis.com/auth/gmail.compose",
   "https://www.googleapis.com/auth/gmail.readonly",
   "https://www.googleapis.com/auth/gmail.send"
  ],

 "content_security_policy":"script-src 'self'  'unsafe-inline' 'unsafe eval'  https://apis.google.com/js/client.js?; object-src 'self'"


}
}

Any help towards fixing this error would greatly be appreciated.

Answer 1

By default Content Security Policy, inline scripts won't be loaded and only local script can be loaded. You could relax the default policy by:

1. Inline Script. Take a look at Official Guide, inline scripts can be whitelisted by specifying the base64-encoded hash of the source code in the policy. See Hash usage for elements for an example.

   But I believe a better way would extract this logic to a separate script and not use inline script.

2. Remote Script. You could whitelist script resources https://apis.google.com/js/client.js?onload=handleClientLoad by the following section in manifest.json

   "content_security_policy":"script-src 'self' https://apis.google.com; object-src 'self'"
   

   Also, I believe a better way could be downloading the remote client.js and include it as a local script.

Please be aware as per the description of Inline Script, unsafe-inline no longer works.

Up until Chrome 45, there was no mechanism for relaxing the restriction against executing inline JavaScript. In particular, setting a script policy that includes 'unsafe-inline' will have no effect.

Answer 2

I solved this by outsourcing everything into the JavaScript file. So instead of the onclick method in the html I have in the JS file:

window.onload = function () {
    document.getElementById("button").onclick = <function>;
}