String prototypes

string.prototype.js

(function () {
  'use strict';

  var proto = String.prototype;

  if (undefined === proto.startsWith) {
    /**
     * Returns true if the string starts with the given one
     *
     * @param {String} str
     * @returns {boolean}
     */
    proto.startsWith = function (str) {
      return 0 === this.indexOf(str);
    };
  }

  if (undefined === proto.endsWith) {
    /**
     * Returns true if the string ends with the given one
     *
     * @param {String} str
     * @returns {boolean}
     */
    proto.endsWith = function (str) {
      var startPos = this.length - str.length;
      return startPos === this.lastIndexOf(str);
    };
  }

  if (undefined === proto.format) {
    /**
     * Similar to String.Format(str, params) behavior (.Net).
     * @returns {String}
     */
    proto.format = function () {
      var s = this, i = arguments.length;
      while (i--) {
        s = s.replace(new RegExp('\\{' + i + '\\}', 'gm'), arguments[i]);
      }
      return s;
    };
  }

  if (undefined === proto.capitalize) {
    /**
     * Capitalize the given string
     *
     * @returns {String}
     */
    if (undefined === proto.toLocaleUpperCase) {
      proto.capitalize = function () {
        return this.charAt(0).toUpperCase() + this.substr(1);
      };
    } else {
      proto.capitalize = function () {
        return this.charAt(0).toLocaleUpperCase() + this.substr(1);
      };
    }
  }

  if (undefined === proto.niceReplace) {
    /**
     * Replace helper
     *
     * @param {Object} dictionary
     * @returns {String}
     */
    /*jshint -W121 */
    proto.niceReplace = function (dictionary) {
      /*jshint +W121 */
      var me = this;
      for (var subStr in dictionary) {
        if (dictionary.hasOwnProperty(subStr)) {
          var newSubStr = dictionary[subStr];
          me = me.split(subStr).join(newSubStr);
        }
      }
      return me;
    };
  }

}(this));