JavaScript language plays a very important role in Web 2.0 application development. JavaScript has its own characteristics different than object-oriented languages and it's not easy for developers to understand. This presentation covers major advanced topics in JavaScript languages, including prototype chain, identifier resolving, "this" keyword, "new" operator, execution context and scope chain and closure. Besides that, it also covers best practices when using JavaScript.

1. Advanced JavaScript Alex Cheng (CHENG Fu)

6. Search for an Identifier Find the property in current object Return the value Value of current object's prototype is not null Return undefined Set current object to the value of its prototype Y Y N N The search process

8. What can JavaScript do for OO enthusiasts?

14. aStudent Student prototype object Person aPerson prototype object getEmail getName new new Student.prototype = new Person(); Search path of aStudent.getName Student 's prototype object -> Person 's prototype object Constructor's prototype Constructor Objects created by new operator Implicit references to constructor's prototype Note: aPerson doesn't exist in the code. Properties

20. What happends when I invoke myFunc() ?

23. E B C A D B1 C1 A2 A1 D1 E1 C2 Scope Chain Prototype Chain Search path : A -> A1 -> A2 -> B -> B1 -> C -> C1 -> C2 -> D -> D1 -> E -> E1

25. A Quiz This quiz is based on http://ejohn.org/apps/learn/#8 Function getSOSNumber is initialized when entering the EC. So it can be invoked even its body appears after a return statement. getSOSNumber is a local variable which is undefined when entering the EC. It's initialized when executing the assign operator. Function declaration v.s. Function expression

28. Why can you use alert() everywhere?

34. Closure? What is it?