String interpolation in Typescript, replacing 'placeholders' with variables

I cannot seem to find a clear enough answer on this topic, so I am asking the question:

In C#, I can do the following, for instance:

var text = "blah blah";
var strTest = String.Format("This is a {0}", text); //output: 'This is a blah blah'

How would I achieve this in Typescript?

Usage:

I am loading a URL from the environment.ts file, and this string URL will need to contain the placeholders, and in my service layer, replace the placeholders with the actual parameters that needs to be passed in.

Solution 1:

Use a template string which are much better than String.Format in my opinion as they do not suffer from poor indexing (wrong placeholder) issues:

var text = "blah blah";
var strTest = `This is a ${text}`;
console.log(strTest);

If I do not know the name of the variables I need to pass in??

Then wrap in a function e.g.

const gen = (text) => `This is a ${text}`;

Solution 2:

I'd suggest using anonymous generator functions in your environments.ts file, so you could pass the variables you need and have the template strings inside this functions. Something like this:

environments.ts

 export const thisIsA = (str: string) => `This is a ${str}`;

Some other file:

import * as env from 'environments';

var text = "blah blah";
var strTest = env.thisIsA(text); //output: 'This is a blah blah'