Introduction to JavaScript

to improve the design, add functionality, validate forms, detect browsers, create cookies and much more

JavaScript is used in millions of Web pages

popular scripting language on the Internet

JavaScript is the most

scripting language of the Web

JavaScript is the

open-source programming language

JavaScript is an

lightweight and interpreted

JavaScript is

embedded directly into HTML pages

JavaScript is usually

interpreted language

JavaScript is an

scripts execute without preliminary compilation

interpreted language

without purchasing a license

JavaScript can be used

• Web Applications

• Mobile Applications

• Web-based Games

• Back-end Web Development

What is JavaScript used for?

used to insert JavaScript into an HTML page

<script>

to define the scripting language

“type”

to close

</script>

codes end with a ;

C++ and Java

;

Optional in JavaScript

;

To put more than one statement on a single line

comment

//

//

Do not put in the front of the first comment

can be inserted almost anywhere into an HTML document

script tag

script is loaded before anyone uses it

Where to place JavaScript?

head section

generates the content of the page

Where to place JavaScript?

body section

unlimited number of scripts both in body and head

Where to place JavaScript?

body and head section

external file written with a .js file extension

Where to place JavaScript?

external javascript

a list of instructions to be executed by a computer

Computer Program

In programming language, these programming instructions are called

statements

a list of programming statements.

JavaScript program

• Values

• Operators

• Expressions

• Keywords

• Comments

Javascript statements are composed of

ignores white spaces.

JavaScript

80 characters

Programmers avoid code lines longer than

break after an operator

JavaScript statement does not fit on one line

inside curly brackets {…}

JavaScript statements can be grouped in code blocks

a keyword

JavaScript script statements often start with

are values that can be processed and calculated

Numbers

are a series of letters and numbers enclosed in quotation marks.

Strings

lets you evaluate whether a condition meets or does not meet specified criteria

Boolean (true/false)

is an empty statement

Null