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Ligouri S Tittus
Ligouri S Tittus

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Java Script (intro)

**1. Histroy of JS

  1. What is java script?
  2. Why we need JS?
  3. How the JS works?
  4. Where we use JS?**

1] History of js:

  • JavaScript was created in 1995 by Brendan Eich, while he was at Netscape.
  • Its original name was Mocha, then LiveScript, before being renamed JavaScript.
  • Microsoft released its own version, called JScript, with Internet Explorer 3.
  • In 1997, Netscape submitted JavaScript to ECMA International for standardization, which led to the first edition of the ECMAScript standard.

  • ECMAScript 3 was a significant update, and there was a planned Edition 4 which was eventually abandoned. Some parts of what was intended in Edition 4 were later folded into ES5.
    **
    2]What is Java Script?**
    JavaScript is a cross-platform, object-oriented scripting language used to make webpages interactive (e.g., having complex animations, clickable buttons, popup menus, etc.). There are also more advanced server side versions of JavaScript such as Node.js, which allow you to add more functionality to a website than downloading files (such as realtime collaboration between multiple computers). Inside a host environment (for example, a web browser), JavaScript can be connected to the objects of its environment to provide programmatic control over them.

  • Object-oriented. No distinction between types of objects. Inheritance is through the prototype mechanism, and properties and methods can be added to any object dynamically.
    -Variable data types are not declared (dynamic typing, loosely typed).

    -Cannot automatically write to hard disk.

3]Why we need JS?

To Make Web Pages Interactive :

Without JS, web pages are static — they just display information.
JS makes them respond to users.
👉 Example: Buttons that show/hide content, image sliders, pop-ups, form validation.
**
To Handle Dynamic Content:**

JS allows content to change without reloading the page.
👉 Example: New tweets appearing on Twitter automatically.

To Validate Forms:

Before sending data to the server, JS checks user inputs.
👉 Example: Checking if an email is valid or a password is strong.

To Build Web Applications:

Modern apps like Gmail, YouTube, and Facebook are powered by JavaScript (and frameworks like React, Angular, or Vue).

To Communicate with Servers:

JS can fetch or send data from servers in the background using AJAX or Fetch API.
👉 Example: Loading comments on a post without refreshing.

For Game and App Development:

You can use JS to create games, mobile apps (with React Native), and even desktop apps (with Electron).

To Control Multimedia and Animations:

JS can play audio/video, animate elements, or create visual effects.

4] How js works?
JavaScript is the brain of a web page — it makes things happen (like clicking buttons, showing popups, or changing colors).

It mainly runs inside the browser (like Chrome, Firefox, Edge), and sometimes on servers (like with Node.js).

  1. Browser loads the web page

When you open a web page:

  • The browser downloads the HTML file.
  • It reads the CSS file to style the page.
  • Then it finds any JavaScript (.js) files and starts executing them. 
<script src="script.js"></script>
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The engine:

Reads your JS code.
Converts it into something the computer understands.
Executes it line by line.

The browser:

JS Engine → Executes code → Interacts with DOM → Handles events → Updates the page dynamically

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