hermanjunge

var now = new Date();

now.format("m/dd/yy");
// Returns, e.g., 6/09/07

// Can also be used as a standalone function
dateFormat(now, "dddd, mmmm dS, yyyy, h:MM:ss TT");
// Saturday, June 9th, 2007, 5:46:21 PM

// You can use one of several named masks
now.format("isoDateTime");
// 2007-06-09T17:46:21

// ...Or add your own
dateFormat.masks.hammerTime = 'HH:MM! "Can\'t touch this!"';
now.format("hammerTime");
// 17:46! Can't touch this!

// When using the standalone dateFormat function,
// you can also provide the date as a string
dateFormat("Jun 9 2007", "fullDate");
// Saturday, June 9, 2007

// Note that if you don't include the mask argument,
// dateFormat.masks.default is used
now.format();
// Sat Jun 09 2007 17:46:21

// And if you don't include the date argument,
// the current date and time is used
dateFormat();
// Sat Jun 09 2007 17:46:22

// You can also skip the date argument (as long as your mask doesn't
// contain any numbers), in which case the current date/time is used
dateFormat("longTime");
// 5:46:22 PM EST

// And finally, you can convert local time to UTC time. Either pass in
// true as an additional argument (no argument skipping allowed in this case):
dateFormat(now, "longTime", true);
now.format("longTime", true);
// Both lines return, e.g., 10:46:21 PM UTC

// ...Or add the prefix "UTC:" to your mask.
now.format("UTC:h:MM:ss TT Z");
// 10:46:21 PM UTC

Needed to make an array of functions, but certain parameter has to vary inside the function:

// The array containing the elements each for every functon
var comments = ['1', '2', '3', '4', '5']

// The function with the different element
function saveComment (callback, i) {
  console.log(comments[i]);
  callback();
}

// Wrapper, (or `currier`)
function fn (i) {
  return function (callback) {
    return saveComment (callback, i);
  };
};

// The array containing the functions
var myArray = [];

// The loop to compose them
for (var j = 0; j < 5; j ++) {
  var saveCommentForI = fn(j);
  myArray.push(saveCommentForI);
};

// Executing our array of functions
for (var k = 0; k < 5; k++) {
  myArray[k](function(){
    console.log('callback invoked')
  });
};

/**
  Result should be:

  $ node test.js
 
  1
  callback invoked
  2
  callback invoked
  3
  callback invoked
  4
  callback invoked
  5
  callback invoked

 */

gist

function containerScope(){
  var a = [];
  var b = {};
  var c = true;
  var d = 22;
  function argumentsObject(a, b, c, d){
    console.log(arguments.length);
    console.log(arguments[0]);//Array
    console.log(arguments[1]);//Object
    console.log(arguments[2]);//true
    console.log(arguments[3]);//22
    arguments[3] = 55;//I have now changed d as well!
    console.log(arguments[3]); 
    console.log(d);
  }
  argumentsObject(a, b, c, d);
}

via SNIPPLR

If you want to check if a variable exist

if (typeof yourvar != 'undefined') // Any scope
if (window['varname'] != undefined) // Global scope
if (window['varname'] != void 0) // Old browsers

via Stackoverflow