javascript comprehensive overview

JavaScriptMohamed Loey

Agenda

Part I: Introduction

Part II: JavaScript Syntax

Agenda

Part I: IntroductionWhat is JavaScript? JavaScript In HTML JavaScript Can

What is JavaScript?• JavaScript is the first Web scripting

language, developed by Netscape in 1995• JavaScript is a scripting language. It is a

lightweight, but powerful, programming language.

• JavaScript similarities to Java/C++• JavaScript is Client-side web programming• JavaScript is the most popular

programming language in the world.

JavaScript In HTML• In HTML, JavaScripts must be inserted

between <script> and </script> tags.• JavaScripts can be put in the <body>

and in the <head> section of an HTML page.

• Two Ways to Insert JavaScript:1. Internal script2. External script sheet

Internal script

• Scripts can be placed in the <body> or in the <head> section of HTML, and/or in both.

• Example:

External script sheet

• Scripts can also be placed in external files.

• External scripts are practical when the same code is used in many different web pages.

• JavaScript files have the file extension .js.• To use an external script, put the name of

the script file in the source (src) attribute of the <script> tag

External script sheet

• Example:

JavaScript Can

• Change HTML Elements• Change HTML Attributes• Change HTML Styles (CSS)• Validate Data

Agenda

Part II: JavaScript Syntax JavaScript is Case Sensitive JavaScript Comments JavaScript Variables JavaScript Conditions JavaScript Loops JavaScript Arrays

JavaScript is Case Sensitive

• In JavaScript all identifiers are case sensitive.

• The variables lastName and lastname, are two different variables.

• The functions myFunction and myfunction, are two different functions.

• JavaScript does not interpret Var; as var.

JavaScript Comments

• Single Line Comments• Single line comments start with //.

• Multi-line Comments• Multi-line comments start with /* and

end with */.

JavaScript Variables

• JavaScript uses the var keyword to define variables

• Example:

JavaScript Conditions

• In JavaScript we have the following conditional statements:1. Use if to specify a block of code to be

executed, if a specified condition is true2. Use else to specify a block of code to be

executed, if the same condition is false3. Use else if to specify a new condition to

test, if the first condition is false4. Use switch to specify many alternative

blocks of code to be executed

JavaScript Conditions

• Example:

JavaScript Loops

• JavaScript supports different kinds of loops:1. for - loops through a block of code a

number of times2. for/in - loops through the properties of an

object3. while - loops through a block of code while

a specified condition is true4. do/while - also loops through a block of

code while a specified condition is true

JavaScript Loops

• Example:

JavaScript Arrays

• JavaScript arrays are used to store multiple values in a single variable.

• Example:

JavaScript Functions

• A JavaScript function is a block of code designed to perform a particular task.

• A JavaScript function is executed when "something" invokes it (calls it).

• Example:

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javascript comprehensive overview

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