Wednesday, February 6, 2013

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.

JavaScript | MDN
A re-introduction to JavaScript

Related posts:
JavaScript Questions and Answers – Part 2
JavaScript Questions and Answers

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