Is there a C# String.Format() equivalent in JavaScript? [duplicate]

Answer 1

I am using:

String.prototype.format = function() {
    var s = this,
        i = arguments.length;

    while (i--) {
        s = s.replace(new RegExp('\\{' + i + '\\}', 'gm'), arguments[i]);
    }
    return s;
};

usage: "Hello {0}".format("World");

I found it at Equivalent of String.format in JQuery

UPDATED:

In ES6/ES2015 you can use string templating for instance

'use strict';

let firstName = 'John',
    lastName = 'Smith';

console.log(`Full Name is ${firstName} ${lastName}`); 
// or
console.log(`Full Name is ${firstName + ' ' + lastName}');