Javascript sprintf

numbred-sprintf.js

// @SOURCE: https://stackoverflow.com/a/4673436/4864081

// First, checks if it isn't implemented yet.
if (!String.prototype.format) {
  String.prototype.format = function() {
    var args = arguments;
    return this.replace(/{(\d+)}/g, function(match, number) { 
      return typeof args[number] != 'undefined'
        ? args[number]
        : match
      ;
    });
  };
}

// "{0} is dead, but {1} is alive! {0} {2}".format("ASP", "ASP.NET")
// ASP is dead, but ASP.NET is alive! ASP {2}

// If you prefer not to modify String's prototype:
if (!String.format) {
  String.format = function(format) {
    var args = Array.prototype.slice.call(arguments, 1);
    return format.replace(/{(\d+)}/g, function(match, number) { 
      return typeof args[number] != 'undefined'
        ? args[number] 
        : match
      ;
    });
  };
}

// String.format('{0} is dead, but {1} is alive! {0} {2}', 'ASP', 'ASP.NET');
// ASP is dead, but ASP.NET is alive! ASP {2}

simple-sprintf.js

// Simple and minimal `sprintf` function in JavaScript. 
function sprintf(format) {
    var args = Array.prototype.slice.call(arguments, 1);
    var i = 0;
    return format.replace(/%s/g, function() {
        return args[i++];
    });
}

also sprintf-js