What is JavaScript ?

JavaScript allows you to make web pages more interactiv by accessing and modifying the content and marckup used in a web page while it is begin viewed in the browser

React to event , its like when a button is pressed pr a lin is clicked ….etc.

Access the content of the page

Modify the content of the page

Program rules or instructions the browser can follow

React to events triggered by the user or browser

A script is a series of instructions that a computer can follow to achieve a goal.

To approach writing a script, break down your goal into a series of tasks and then work out each step needed to complete that task (a flowchart can help).

OPERATORS

EXPRESSIONS THAT JUST ** ASSIGN A VALUE TO A VARIABLE **

var color = 'beige';

EXPRESSIONS THAT USE ** TWO OR MORE VALUES TO RETURN A SINGLE VALUE **

var area = 3 * 2;

  1. ASSIGNMENT OPERATORS color = 'beige';

  2. COMPARISON OPERATORS buy = 3 > 5;

  3. ARITHMETIC OPERATORS area = 3 * 2;

  4. LOGICAL OPERATORS buy= (5 > 3) && (2 < 4);

  5. STRING OPERATORS greeting= 'Hi 1 + 'Mol ly';

WHAT IS A FUNCTION?

Functions let you group a series of statements together to perform a specific task. If different parts of a script repeat the same task, you can reuse the function (rather than repeating the same set of st atements).

var msg = 'Sign up to receive our newsletter for 10% off!';
function updateMessage() {
var el = document.getElementByld('message'};
el .textContent = msg;
}
updateMessage(};

function

and to call the function we write : function

function

This function will calculated and return the area of a rectangle .

he git the width and height as a parameter , and multiplying the width and height and return area .

example

getArea(2,2);

output:
4

we can assignment a function to varibale like this :

var wallOne= calculateArea(5,2);