Use of String.Format in JavaScript?

Question

This is driving me nuts. I believe I asked this exact same question, but I can\'t find it any more (I used Stack Overflow search, Google Search, manually searched my po

Answer 1

//Add "format" method to the string class
//supports:  "Welcome {0}. You are the first person named {0}".format("David");
//       and "First Name:{} Last name:{}".format("David","Wazy");
//       and "Value:{} size:{0} shape:{1} weight:{}".format(value, size, shape, weight)
String.prototype.format = function () {
    var content = this;
    for (var i = 0; i < arguments.length; i++) {
        var target = '{' + i + '}';
        content=content.split(target).join(String(arguments[i]))
        content = content.replace("{}", String(arguments[i]));
    }
    return content;
}
alert("I {} this is what {2} want and {} works for {2}!".format("hope","it","you"))

You can mix and match using positional and "named" replacement locations using this function.