Convert this string formatting from C# to JS

I want to convert this C# code to JS:

    myTimer -= Time.deltaTime;
    int minutes = Mathf.FloorToInt(myTimer / 60F);
    int seconds = Mathf.FloorToInt(myTimer - minutes * 60);
 
    string niceTime = string.Format("{0:0}:{1:00}", minutes, seconds);
 
    myLabel.text= niceTime;

Here is what I have so far:

    myTimer -= Time.deltaTime; // Count down the time in seconds on timer
 	var minutes :int = Mathf.FloorToInt(myTimer / 60F);
    var seconds :int = Mathf.FloorToInt(myTimer - minutes * 60);
 
 	string niceTime = string.Format("{0:0}:{1:00}", minutes, seconds);

I am stuck on the string formatting part, how do I write this in JS?

As with other variables, niceTime needs to be declared with ‘var’. And for some unknown reason (to me), the string class is access in Javascript with an upper case ‘S’. Functionality is the same since it is .NET.

 var niceTime = String.Format("{0:0}:{1:00}", minutes, seconds);