JavaScript: Understanding the weird parts 

JavaScript? 

JavaScript? - Started out as language to make web pages dynamic 

JavaScript Everywhere! 

The Sad Part 

Weirds 

Weird 00 

Weird 01 

var foo = ‘1’ + 2; console.log(foo); var data = data || {}; console.log(data); 

Weird 02 

var a; console.log(a); if (a === undefined) { console.log('a is undefined!'); } else { console.log('a is defined!'); } 

Weird 03 

var Tony = { firstname: 'Tony', lastname: 'Alicea', address: { street: '111 Main St.', city: 'New York', state: 'NY' }, fullname: function(){ return firstname + ‘ ’ + lastname; } }; var firstnameKey = ‘firstname’; console.log(Tony.firstnameKey); console.log(Tony.firstname); console.log(Tony.fullname); 

Weird 04 

function a() { console.log(this); this.newvariable = 'hello'; } var b = function() { console.log(this); } a(); console.log(newvariable); // not good! 

Weird 05 

var foo = function() { var bar = 'baz' return { bar: bar } } console.log(foo()); 

Weird Undefined 

Get JavaScripty! 

Questions? 

Thanks!