Introduction to JavaScript

Interactive Web Development

What is JS? JavaScript is a cross-platform, object-oriented scripting language used to make webpages interactive (e.g., having complex animations, clickable buttons, popup menus, etc.).

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JS files are placed in <script> tag in html, and by default the display property of script is none

Running JavaScript in a Web Browser:

Create an HTML file: Create a new HTML file using a text editor.

Internal JS

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
	<script>
	  alert("Hello, World!");
	</script>
</body>
</html>

External JS

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script src="script.js"></script>
</body>
</html>

Open in a Web Browser: Save the HTML file and open it in a web browser.
View Console Output: Open the browser's developer tools (by right-clicking on the page, selecting "Inspect," and navigating to the "Console" tab) to view console output and errors.

Case Sensitive
cout<<”Hello World”; → console.log(’Hello World’)
In C++ we get output in console, to see the output of JS:
- Go to Browser, open Inspect / Developer Tools( Ctrl+Shift+i )
- Go to Console Tab.

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<aside> 💡 ECMAScript === JavaScript

</aside>