Check whether user has a Chrome extension installed

Question

I am in the process of building a Chrome extension, and for the whole thing to work the way I would like it to, I need an external JavaScript script to be able to detect if

Answer 1

I thought I would share my research on this. I needed to be able to detect if a specific extension was installed for some file:/// links to work. I came across this article here This explained a method of getting the manifest.json of an extension.

I adjusted the code a bit and came up with:

function Ext_Detect_NotInstalled(ExtName, ExtID) {
  console.log(ExtName + ' Not Installed');
  if (divAnnounce.innerHTML != '')
    divAnnounce.innerHTML = divAnnounce.innerHTML + "
"

  divAnnounce.innerHTML = divAnnounce.innerHTML + 'Page needs ' + ExtName + ' Extension -- to intall the LocalLinks extension click here';
}

function Ext_Detect_Installed(ExtName, ExtID) {
  console.log(ExtName + ' Installed');
}

var Ext_Detect = function (ExtName, ExtID) {
  var s = document.createElement('script');
  s.onload = function () { Ext_Detect_Installed(ExtName, ExtID); };
  s.onerror = function () { Ext_Detect_NotInstalled(ExtName, ExtID); };
  s.src = 'chrome-extension://' + ExtID + '/manifest.json';
  document.body.appendChild(s);
}

var is_chrome = navigator.userAgent.toLowerCase().indexOf('chrome') > -1;

if (is_chrome == true) {
  window.onload = function () { Ext_Detect('LocalLinks', 'jllpkdkcdjndhggodimiphkghogcpida'); };
}

With this you should be able to use Ext_Detect(ExtensionName,ExtensionID) to detect the installation of any number of extensions.