get-or-else/index.js

Get Or Else in Javascript

/**
 * @param {Array} get - the namespace including 2 parts as follows...
 * @param {Object} get[0] - the root object to your namespace.
 * e.g. this, window, someObj (Must exist).
 * @param {String} get[1] - a string representation of the namespace you
 * are targeting to get it's property. e.g. 'a.b.c.d'
 * @param {Any type of object} backup - the backup value to return if the requested namespace does not yeild a result
 * @returns the item you hope to get from your namespace, or the backup item if it does not exist.
 * @example
 *
 * GIVEN
 * window.a = {x:4}
 *
 * get([window, 'a.b.c'], ':/')
 * // => ':/' - namespace does not exist, so backup value is used
 *
 * get([window,'a'], {})
 * // => {x:4} - namespace exists so expected value is returned
 */

var get = function( get, backup ) {
  var contextObjext = get[0];
  if (!contextObjext) return backup;
  var namespace = get[1].split('.');
  var value = contextObjext;
  // reassigns to obj[key] on each array.every iteration
  return ( namespace.every( function(key){ return (value = value[key]) != undefined; }) )
    ? value
    : backup;
};

module.exports = get;