Google Analytics Typescript

GoogleAnalytics.ts

/// <reference path="./../../paket-files/borisyankov/DefinitelyTyped/google.analytics/ga.d.ts" />

export var gaNewElem : any = {};
export var gaElems : any = {};

function gaInit(){
  var currdate : any = new Date();
  
  /* tslint:disable:no-string-literal */
  /* tslint:disable:semicolon */
  /* tslint:disable:no-unused-expression */
  // This code is from Google, so let's not modify it too much, just add gaNewElem and gaElems:

  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*currdate;a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  })(window,document,'script','//www.google-analytics.com/analytics.js','ga', gaNewElem, gaElems);
  /* tslint:enable:no-unused-expression */
  /* tslint:enable:semicolon */
  /* tslint:enable:no-string-literal */

  ga('create', 'UA-XXXXXXXX-X', 'auto');
  ga('send', 'pageview');
}

(function() {
  gaInit();
});

on my screen, there's a problem of cannot find name 'ga'. can you help me why? thanks

In the tsconfig file, type sources can be specified in compilerOptions -> types.

{
   "compilerOptions": {
       "types" : ["google.analytics"]
   }
}

If I'm readying the docs correctly, TypeScript will also pull from the node_moduels/@types if types and typeRoots are not specified, but if they are this settings will need to be included.
https://www.typescriptlang.org/docs/handbook/tsconfig-json.html