JavaScript (OCR A Level Computer Science)

JavaScript

What is JavaScript?

JavaScript is a programming language that adds interactivity and dynamic functionality to webpages. It allows a webpage to manipulate HTML elements, perform calculations, handle user input, and more. 

Purpose of JavaScript

• JavaScript is primarily used for client-side scripting, meaning it runs directly in the web browser of the user

• Its purpose is to enhance webpages by enabling interactive features, dynamic content, form validation, and data manipulation

  • Interactive features include features like image sliders, drop-down menus, or interactive maps, like allowing users to zoom in and out on a Google Maps element embedded in the website

  • Dynamic content could be loading more articles or posts when a user reaches the end of a page (infinite scrolling), or changing the content based on the user's actions, such as showing different product descriptions when a user hovers over product images

  • Form validation could be checking that all required fields have been filled in, that an email address has the correct format, or that passwords meet certain strength requirements

  • Data manipulation could involve filtering a list of products based on user-selected criteria, sorting a table of data, or creating a dynamic chart that updates in real-time as new data comes in

• JavaScript can respond to user actions, update the content of HTML elements, and communicate with servers to retrieve or send data

Data Types in JavaScript

Data Types in JavaScript

• A data type is a classification of data into groups according to the kind of data they represent

• Computers use different data types to represent different types of data in a program

• The basic data types include:

  • Integer: used to represent whole numbers, either positive or negative

    • Examples: 10, -5, 0

  • Real: used to represent numbers with a fractional part, either positive or negative

    • Examples: 3.14, -2.5, 0.0

  • Char: used to represent a single character such as a letter, digit or symbol

    • Examples: 'a', 'B', '5', '$'

  • String: used to represent a sequence of characters

    • Examples: "Hello World", "1234", "@#$%

  • Boolean: used to represent true or false values

    • Examples: True, False

We can declare variables as follows:

It is important to choose the correct data type for a given situation to ensure accuracy and efficiency in the program.