Extending the String class with helpful functions for templating

string-utils.js

/**
 * Javascript implementation of String.format or printf
 *
 * example of usage
 * 'vincenty lat1: {0}  lon1: {1}  lat2: {2}  lon2: {3}'.format(lat1, lon1, lat2, lon2)
 *
 * outputs
 * vincenty lat1: 40.689247  lon1: -74.044502  lat2: 40.7747222222  lon2: -73.8719444444
 * 
 * http://stackoverflow.com/questions/610406/javascript-equivalent-to-printf-string-format/4673436#comment46715555_4673436
 *
 */
if (typeof String.prototype.format === 'undefined') {
    String.prototype.format = function () {
        "use strict";
        var args = arguments;
        return this.replace(/\{(\d+)\}/g, function (match, number) {
            return typeof args[number] !== 'undefined' ? args[number] : match;
        });
    };
}

// TODO: untested
// inspired by Douglas Crockford's Javascript the Good Parts
// JSLint issues
// insecure ^   --> '^' '.' match more material than might be expected, allowing attackers to confuse applications.
// These forms should not be used when validating in secure applications.
if (typeof String.prototype.supplant === 'undefined') {
    String.prototype.supplant = function (o) {
        return this.replace(/{([^{}]*)}/g, function (match, number) {
            return typeof o[number] === 'string' ? o[number] : match;
        });
    };
}