ahmadajmi

var foo;
foo;              // return undefined

function bar(x){
  return x;
}

bar();           // return undefined

ahmadajmi

var boo = {x:15};
boo.x;            // return 15
boo.y;           // return undefined

ahmadajmi

var foo = undefined;  // return undefined 
var foo;              // return undefined  

ahmadajmi

var foo = "0";             //  true  becuse "0" !== 0
var foo = "false";         //  true  becuse "false" !== false

ahmadajmi

var passion = {
    frontend: "Javascript",
    backend: "Ruby on Rails"
};

passion.frontend;      // use dot notation and return "Javascript"
passion["backend"];    // use subscript notation and return "Ruby on Rails"

ahmadajmi

4 + 5 + 1;              // return 10
'4' + 5 + 1;           // return '451'
4 +  5 + '1';          // return '91'

// can convert strings to numbers

+"45";                 // return 45

// also
Number("45");          // return 45

ahmadajmi

var foo = 22;
var t = foo && 23;
t;                     // return 23

var t = foo || 23;
t;                     // return 22

var bar = true;
!bar;                 // return false
!!bar                 // return true

ahmadajmi

JS Conf slides - 2011

Track A

• Bytes and Blobs by David Flanagan
• Conference Wifi Redux by Malte Ubi
• Sashimi - https://github.com/cramforce/Sashimi
• Run Your JS everywhere with Jellyfish by Adam Christian - http://jelly.io Project
• Fighting Crime and Kicking Apps with Batman.js by Nick Small
• Hello Jo by Dave Balmer - Project - http://joapp.com

ahmadajmi

function singleVarPattern() {
  var x = 1,
      z = 2,
      arr = [],
      obj = {};
}

ahmadajmi

           __
	  |   r if r > 0         # This construct is called a case analysis
	  |													
	  |__ 0 if r = 0
    |R| = |
	  |
	  |__ -r if r < 0