Understanding JavaScript and Coding Essentials

Agenda

Basic Information
How to include JS Code into HTML
Comments
Variables
Data Types
Type Casting
Functions in

Basic information

JavaScript - dynamic computer programming language.
It is most commonly used

1. Inline JavaScript:

2. Internal tag
3. External file:

Comments

Comments - part of the program text which will be ignored

Variables

Variable – symbolic name associated with a value and whose associated

Declaration and initialization

var – special keyword for declaration of variables
In JavaScript

var

Global and local

JavaScript has two types of variables:
global - exist

Data types

JavaScript has 6 base data types:
Number – scalar type

Number, Boolean and String

var n = 10; or var n =

Null and Undefined

var n = null;
//null variables can have only

Type casting

var a, b, c;
a = 10;
b = true;

Type casting

Rules of typing casting:
All scalar types try to convert itself

Functions

In mathematics:
In classical programming

[3]

Function is a relation between a set of

Example

var i, base, power, result;
base = 2; power = 2; result

Function Declaration

function name (a, b) {
return a + b;
}

[1]

*

Function call

Call - operation for execution of function.
( ) –

Example

var out;
out = pow(2, 2);
console.log(out);
out = pow(3, 4);
console.log(out);
function pow (base, power)

Code processing

var a = 10;
test();
function test () {
a = 30;

Code processing

var a = 10;
test();
function test () {
a = 30;

Code processing

var a = 10;
test();
function test () {
a = 30;

Code processing

var a = 10;
test();
function test () {
a = 30;

Code processing

var a = 10;
test();
function test () {
a = 30;

Function Declaration and Expression

function name () {
body;
}

[1]

var name =

Additional Facts About Functions

Functions in JavaScript are Objects.
As a result, functions

Program flow

Operators in a program processed in linear order: from top

Conditions: if-else

Very often we have to choose Most of algorithms have

Conditions: if-else

Example:

function discount (type) {
if (type === “silver”) {

Conditions: ?:

Sometimes if-else too bulky. If we need to initialize a

Conditions: ?:

function discount (type) {
if (type === “silver”) {
price

Loops: for

Loops are used when algorithm requires repeating of statements.
First of

Loops: while and do-while

Two others types of loops: while and do-while

while

Loops: examples

Example 1:

for (var i = 0; i < 5;

Loops: break and continue

There are two keywords for loops control

Switch

Switch statement allows to select one of many blocks of code

Switch

Example:

This switch looks for the word equivalent for a mark

Practice Task