Javascript session 01 - Introduction to Javascript

History of Javascript First appeared in 1995 Main purpose was Input validation Netscape Navigator 3 Cmm -> ScriptEase -> Expresso Pages Brendan Eich Mocha -> LiveScript -> Javascript IE 3 & Jscript ECMAScript – 1997

Javascript Implementation The Core (ECMAScript) Document Object Model (DOM) Browser Object Model (BOM)

Implementations of ECMAScript Javascript JScript ActionScript Ejscript JSCript 3.0

DOM API for XML & HTML documents Hierarchy of Nodes

<html> <head> <title>DOM Example</title> </head> <body> <p>Welcome to the DOM</p> </body> </html> HTML Document

HTML HEAD TITLE DOM Example BODY P Welcome to the DOM DOM Hierarchy Representation

DOM Control of Content & Structure Add, remove and modify nodes Standards Levels DOM Level 0 DOM Level 1 DOM Level 2 DOM Level 3

DOM Level 0 Netscape Navigator 3 & IE 3 Primitive Level 1 DOM Core DOM HTML

DOM Level 2 Views Events Styles Traversal Range

DOM Level 3 DOM Load & Save DOM Validation Xpath XML Base

DOM Other DOMs Scalable Vector Graphics (SVG) Mathematical Markup Language (MathML) Synchronized Multimedia Integration Language (SMIL)

DOM Browser Support Level 0 Netscape Navigator 4 Internet Explorer 4 Opera 1 – 6 Level 1 Netscape Navigator 6+ Internet Explorer 5+ Opera 7+ Safari

DOM Browser Support Cont.. Level 2 Internet Explorer 8 Safari 2+ Chrome Opera 7+ Level 3 Safari 3+ Chrome 2+ Firefox 1+ Opera 9+

BOM Internet Explorer 3 Interact with the Browser No Standards

BOM Opening windows – window.open Move, resize & close windows Navigator object location object screen object Cookie XMLHttpRequest

Browser Engines Trident Gecko WebKit KHTML Presto

Javascript Language ECMAScript 3rd Edition C, Perl Syntax Case Sensitive

Identifiers A-Z, a-z, 0-9, $, _ Cannot use Keywords and reserved words Comments //single-line comments /* */ multi-line comments

Statements Ends with ; is optional but recommended var sum = a + b var difference = a – b;

Statements Multiple statements wrap in { } if (true === true) { varmsg = “hello”; alert(msg + “world”); }

break else new var case finally return void catch for switch while continue function this with default if throw delete in try do instanceoftypeof Keywords

abstract enumint short boolean export interface static byte extends long super char final native synchronized class float package throws constgoto private transient debugger implements protected volatile double import public Reserved Words

Variables Loosely typed Can hold any data Can be modified and contain different type of value ‘var’ scope

function myFunction () { varmyVariables = ‘some string’; } alert(myVariables); //undefined var a = 1, b = ‘hello’, myArray = {};

Datatypes Five primitive datatypes Undefined Null Boolean Number String ‘typeof’ operator ‘objects’

Undefined var temp; alert(temp); //undefined alert(typeof temp === ‘undefined’) //true

Null Empty object pointer var temp = null; alert(null == undefined) //true alert(null === undefined) //false

Boolean Boolean() true false String non-empty string empty string Number non-zero 0 Object any object Undefined – false Null - false

Number Integers & floating point values varintNum = 100; //integer varoctNum = 070; //Octal for 56 varhexNum = 0xA; //Hex for 10 var floatNum1 = 1.1; //float var floatNum2 = 1.; //1 integer var floatNum3 = 0.1; //1 integer varlrgFloat = 3.125e7; //31250000 //3.125 * 10^7

Number NaN – not a number isNaN() NaN === NaN isNaN(NaN); //true isNaN(10); //false isNaN(’10’); //false isNaN(‘cool’); //true isNaN(true); //false

Number Number() Number.MIN_VALUE NUMBER.MAX_VALUE Infinity isFinite()

Javascript session 01 - Introduction to Javascript

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