sub.js

// Sub utility
var sub = function(str, obj) {
  var keys = Object.keys(obj);

  keys.map(function(key) {
    var re = new RegExp('{' + key + '}', 'gm');
    str = str.replace(re, obj[key]);
  });

  return str;
};

module.exports = sub;

var sub = require("sub");

var template = "My favourite month is {month}";

sub(template, {
  month: "December"
});

// My favourite month is December