JavaScript Questions and Answers - Part 2

Continue random JavaScript Questions and Answers from previous post.

What are difference between global and local variables? 
A variable that is declare outside of a function is a global variable, and its value is accessible and modifiable throughout your program. A variable that is declared inside a function is local. It is created and destroyed every time the function is executed, and it cannot be accessed by any code outside the function. ( msdn.microsoft.com )

How we define a class in JavaScript?
JavaScript does not have a class definition separate from the constructor. Instead, you define a constructor function to create objects with a particular initial set of properties and values. Any JavaScript function can be used as a constructor. You used the new operator with a constructor function to create a new object. ( developer.mozilla.org )

What is a JavaScript function?
JavaScript function is a block of code that will be executed when it was called by external code. A function begin with the function keyword, followed by the name, list of parameters if any, and a block of codes inside a curly braces. Function can return a value. Arguments are passed to function by a value.

What is a function expression?
A function expression is a function defined inside an expression. A function name in function expression can be omitted, in which case the function is anonymous. Example: var foo = function () { return 5; }
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JavaScript Questions and Answers – Part 2
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JavaScript Questions and Answers

What is JavaScript?
JavaScript is the object oriented scripting language developed by Brendan Eich, an engineer at Netscape, in 1995. It is also known as Mocha, LiveScript, JScript, ECMAScript, and it is one of the world's most popular programming languages.

Is JavaScript subset of Java?
No. Although Javascript's syntax came from Java and C, they are difference. JavaScript developed by Netscape. Java developed by Sun.

• Java is an OOP programming language while Java Script is an OOP scripting language.
• Java creates applications that run in a virtual machine or browser while JavaScript code is run on a browser only.
• Java code needs to be compiled while JavaScript code are all in text.

What are JavaScript types?

• Number.
• String.
• Boolean.
• Object: Function, Array, Date, RegExp
• Null.
• Undefined.

What is the difference between undefined value and null value?
undefined means a variable has been declared but has not yet been assigned a value. undefined is a property of the global object, i.e. it is a variable in global scope.

null is an assignment value. It is a JavaScript keyword that indicates a variable has a no value. null is a literal (not a property of the global object like undefined can be).

What is jQuery?
jQuery is a fast, small, and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers. With a combination of versatility and extensbility, jQuery has changed the way that millions of people write JavaScript.
Source: Jquery.com

Reference:
JavaScript | MDN
A re-introduction to JavaScript


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JavaScript Questions and Answers – Part 2
JavaScript Questions and Answers

Microsoft Exam 70-480: Programming in HTML5 with JavaScript and CSS3

I passed the Microsoft Exam 70-480 Programming in HTML5 with JavaScript and CSS today. I am so happy. I took this exam for FREE! using this voucher code: HTMLJMP (voucher code available through 3/31/2013 or while supplies last). In the past few months, I spent sometime to learn and using HTML5, CSS3, JavaScript and JQuery. Here are some resources I used to learn:

• Dive Into HTML5 by Mark Pilgrim with contributions from the community
• Microsoft Virtual Academy: Developing in HTML5 with JavaScript and CSS3 Jump Start
• Microsoft Channel 9: HTML5 & CSS3 Fundamentals: Development for Absolute Beginners
• Microsoft Channel 9: Javascript Fundamentals: Development for Absolute Beginners
• HTML5 Rocks - A resource for open web HTML5 developers
• W3.org: HTML5: Edition for Web Authors 
• Mozilla Developer Network: HTML5
• Microsoft:  Internet Explorer 10 Guide for Developers (Windows)
• CSS Font-Size: em vs. px vs. pt vs. percent | Kyle Schaeffer - Web Design and SharePoint Branding
• W3Schools.com:  HTML5 Introduction
• TechExams.net: 70-480 - Programming in HTML5 with JavaScript and CSS3
• Free video lession from Lynda.com: CSS, HTML5