How to make a string constant in angular 4?

Question

In my service, I am using a http post. I want to set the URL as a constant.

return this.http.get(this.config.API_URL+\'users\', options).map(res=&g         


        

Answer 1

You can simply export a constant using es6/typescript modules if that's all you need:

constants.ts:

export const API_URL: string = 'api/url';

And import where needed:

import { API_URL } from './constants.ts';

...

return this.http.get(API_URL+'users', options)
                .map(res=>res.json());

or if you have many constants you can import them all:

import * as constants from './constants.ts';

...

return this.http.get(constants.API_URL+'users', options)
                    .map(res=>res.json());

If you want to make your constants configurable per application on startup, you can use providers. Check out the top answer in this link: how do I get angular2 dependency injection to work with value providers