Course Content
Introduction to JavaScript
JavaScript is one of the most popular and widely used programming languages in the world. It plays a crucial role in web development, enabling dynamic content, interactivity, and enhanced user experiences in web pages and applications. Let’s dive into what JavaScript is, its history, and how it fits into the modern web.
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How to Add JavaScript?
Before diving into the basics of JavaScript, it’s essential to understand how to include JavaScript in an HTML file. There are three main ways to do this:
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Different Ways to Output Data
JavaScript provides several ways to "display" or output data, allowing you to present dynamic content to users in various ways. Each method serves a different purpose and is used in different scenarios depending on the requirements. Here are the primary methods for displaying data using JavaScript:
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Variables and Constants
Variables and constants in JavaScript are used to store data values. Depending on how you declare them, their value can be changed or fixed.
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Data Types
JavaScript provides different types of values that can be stored in variables. These are categorized into two types: Primitives and Non-Primitives.
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Conditional Statements (if, else if, else)
Conditional statements execute different actions based on different conditions.
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Arrays
In JavaScript, an array is a special type of object that stores an ordered collection of values (elements). Arrays are zero-indexed, meaning the first element is accessed with index 0.
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DOM Manipulation
DOM Manipulation is the process of using JavaScript to interact with and modify the HTML and CSS of a webpage. The DOM is essentially the structure of the webpage, represented as nodes, which can be elements, attributes, or pieces of text.
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String Functions in JavaScript
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Number Functions in Javascript
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RegEx (Regular Expressions) in JavaScript
Regular expressions (regex) are patterns used to match sequences of characters in strings. They are powerful tools for searching, validating, and manipulating text.
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JavaScript Modules
JavaScript modules allow developers to split code into reusable pieces that can be imported and exported across files. This makes code more maintainable, reusable, and organized.
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JavaScript JSON (JavaScript Object Notation)
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JavaScript Style Guide
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JavaScript Best Practices
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JavaScript
About Lesson

An EventListener is a function that listens for a specified event on an element and triggers a callback function when that event occurs.

addEventListener() is the primary method for listening to events. It allows you to attach an event to an element and define the action to take when the event occurs.

Syntax:

JavaScript
element.addEventListener("eventType", callbackFunction);
  • eventType: The type of event (e.g., click, submit).
  • callbackFunction: The function that executes when the event occurs.

Example:

JavaScript
let button = document.querySelector("#myButton");
button.addEventListener("click", function() {
  alert("Button was clicked!");
});

Here, an event listener is added to button. When the button is clicked, an alert box appears with the message “Button was clicked!”.

  • Multiple listeners: You can add more than one event listener to an element for the same event type.
  • Flexible handling: You can use functions as callbacks directly or separately as standalone functions.
  • Control over event phases: You can specify whether the listener triggers during the capture or bubble phase.