Call a function of external js file in angular 5 component

Question

Under index.html I have delcared an external js file like

Answer 1

Follow below steps in your component:-

1) First add a reference of your external JS file for importing it to the component. 
   Import * as abcJS from '/YourExternalJS.js';

2) Now declare a "var" of the same name that your function has inside external JS.
   declare var cartstack_updatecart: any;

3) ngOninit(){
 cartstack_updatecart();
 }

4) Do remember that your JQuery should be loaded first than your external JS file.

I have called that function on ngoninit lifecycleHook. Also instead of declaring external JS file inside Index.html, I would rather suggest you to declare it in angular-cli.json file in scripts array. All the best.