Formats a string like sprintf

string-formatter.js

var formatString = (function()
{
    var replacer = function(context)
    {
        return function(s, name)
        {
            return context[name];
        };
    };

    return function(input, context)
    {
        return input.replace(/\{(\w+)\}/g, replacer(context));
    };
})();

//usage
formatString("Hello {name}, {greeting}", {name: "Steve", greeting: "how's it going?"});