JavaScript Overview and Basics

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Questions and Answers

What is the primary purpose of JavaScript?

JavaScript is a scripting language used to create interactive and dynamic web pages.

JavaScript is a compiled language.

False (B)

The syntax of JavaScript was heavily influenced by Java.

True (A)

What is the official name of the standard for JavaScript?

<p>ECMAScript</p> Signup and view all the answers

What are some of the key features of JavaScript?

<p>Object Orient Script Language (A), Interpreter Centered (B), Statements Looping (C), Ability to perform (D), Case Sensitive format (E), Client edge Technology (F), Handling Events (G), Validation of User's Input (H), Else and If Statement (I), Light Weight and delicate (J)</p> Signup and view all the answers

Where is JavaScript typically executed?

<p>Client-side (in the browser)</p> Signup and view all the answers

What is the primary use of Javascript on web pages? Choose the best answer from the options below.

<p>Making web pages interactive, such as using dropdown menus, animations, and form validations. (B)</p> Signup and view all the answers

Which HTML tag is used to embed JavaScript code on a web page?

<p><code>&lt;script&gt;</code> (C)</p> Signup and view all the answers

HTML comments can be used to comment JavaScript code.

<p>True (A)</p> Signup and view all the answers

How can we include JavaScript code in an HTML document?

<p>All of the above (D)</p> Signup and view all the answers

What does the document.write( ) method do in JavaScript?

<p>The <code>document.write()</code> method writes text directly into the HTML document.</p> Signup and view all the answers

What are JavaScript variables?

<p>Variables are containers that can store and manipulate data within your JavaScript code.</p> Signup and view all the answers

Variables in JavaScript are 'case sensitive'. What does 'case sensitive' mean?

<p>A variable name with a lowercase letter is different than a variable name with an uppercase letter. (B)</p> Signup and view all the answers

What are the common JavaScript operators?

<p>Common operators in JavaScript include arithmetic operators (like +, -, *, /), assignment operators (like =, +=, -=), comparison operators (like ==, ===, !=, !==, &gt;, &lt;, &gt;=, &lt;=), and logical operators (like &amp;&amp;, ||, !) among others.</p> Signup and view all the answers

What is the difference between the == and === operators in JavaScript?

<p>The <code>==</code> operator checks for equality in value, while the <code>===</code> operator checks for equality in both value and data type.</p> Signup and view all the answers

What does the if statement do in JavaScript?

<p>The <code>if</code> statement allows you to execute a block of code only if a given condition is true. It helps you create conditional logic in your program.</p> Signup and view all the answers

What data types are defined in the latest ECMAScript standard?

<p>Boolean, null, undefined, number, string, object, symbol (C)</p> Signup and view all the answers

What does the switch statement offer in JavaScript?

<p>The <code>switch</code> statement provides a more efficient way to evaluate multiple possible conditions against a single value, effectively acting as a 'multi-way if' statement.</p> Signup and view all the answers

What are the main elements of the JavaScript Statements?

<p>Components of a JavaScript statement include Expressions (represent value), Values (data like numbers, strings), Operators (perform actions on values), Keywords (reserved words with specific meaning, like 'var'), and Comments (non-executable notes within the code).</p> Signup and view all the answers

Flashcards

JavaScript

A programming language used to make websites interactive.

Client-Side Scripting

Running JavaScript code in the user's web browser.

JavaScript Syntax

Set of rules for writing and interpreting JavaScript code.

Variables

Containers that store data values in JavaScript.

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Functions

Blocks of code that perform specific tasks.

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Statements

Instructions that JavaScript executes.

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Operators

Symbols used to perform operations on values.

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Data Types

Categories of data values (e.g., numbers, text).

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Objects

Collections of data and functions.

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document.write()

Writes text directly to the HTML output.

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window.alert()

Displays an alert box to the user.

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console.log()

Writes output to the browser's developer console.

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getElementById()

Retrieves an HTML element by its ID.

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innerHTML

Sets or gets the HTML content of an element.

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External JavaScript File

Separate JavaScript file linked to an HTML page.

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Inline JavaScript

JavaScript code embedded within an HTML tag.

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Internal JavaScript

JavaScript code placed within the head section of HTML.

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Conditional Statements (if/else)

Execute code blocks based on conditions.

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Loops (for, while)

Repeat code blocks multiple times.

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Event Handling

Responding to user actions (e.g., clicks).

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Webpage Interactivity

Making a webpage dynamic and responsive to user interaction

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Weak Typing

JavaScript doesn't require explicit declaration of variable data types.

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Object-Based Programming

JavaScript uses objects to organize data and actions.

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Study Notes

JavaScript Overview

  • JavaScript is a client-side scripting language
  • It's used to make websites more functional and interactive
  • JavaScript is not the same as Java
  • It's loosely based on Java syntax

JavaScript Objectives

  • Understand the concept of JavaScript
  • Know the JavaScript syntax
  • Use JavaScript in projects

JavaScript Basics

  • Introduction to JavaScript
  • How to enable JavaScript
  • JavaScript syntax
  • JavaScript operators
  • JavaScript variables
  • JavaScript functions
  • JavaScript events
  • JavaScript popup boxes
  • JavaScript and HTML
  • External JavaScript file
  • JavaScript statements
  • JavaScript If Statement
  • JavaScript switch statement
  • JavaScript While loop
  • JavaScript for loop
  • JavaScript try catch
  • JavaScript escape characters
  • JavaScript void(0)

What is JavaScript?

  • JavaScript is a programming language
  • It's an object-based (but not object-oriented) programming language, not object oriented
  • It's weakly typed
  • It's client-side interpreted
  • Designed by Brendan Eich for Netscape
  • Originally called Mocha, then LiveScript, then JavaScript
  • The official standard is ECMAScript

JavaScript Features

  • Object-oriented scripting language
  • Client-edge technology
  • Handling events
  • Statements and looping
  • Lightweight and delicate
  • Case sensitive format
  • Interpreter-centered
  • Validation of user input
  • Else-if statements

What do I need to create JavaScript?

  • A text editor (Notepad, Pico, Simpletext, etc) or an HTML editor
  • A web browser (Chrome, Safari, Edge, Firefox) with JavaScript enabled

JavaScript Syntax

  • JavaScript syntax is a set of rules for writing and interpreting the language
  • It's loosely based on Java syntax.
  • Includes variables, functions, statements, operators, data types, and objects

JavaScript Syntax – Continued

  • The <script> tags define JavaScript code sections
  • The type attribute specifies the language (e.g., text/javascript)
  • HTML comments (<!-- -->) are optional but recommended for JavaScript code enclosed within the script tags
  • Using document.write() displays output on the webpage

Where to put JavaScript?

  • Between HTML head tags
  • Within HTML body tags
  • In an external file

JavaScript Display

  • Writing into an HTML element using innerHTML
  • Writing to the HTML output using document.write()
  • Writing to an alert box using window.alert()
  • Writing to the browser console using console.log()

JavaScript Statements

  • JavaScript statements use expressions, values, operators, keywords, and comments
  • Variables (like x, y, z) store data

JavaScript Arithmetic Operators

  • List of Arithmetic operators, with example outputs and equivalent expressions
  • Include (+, -, *, /, %, ++, --)

JavaScript Assignment Operators

  • List of Assignment operators, with example outputs and equivalent expressions
  • Include (=, +=, -=, *=, /=, %= )

JavaScript Comparison Operators

  • List of Comparison Operators with descriptions (e.g., ==, ===, !=, !==, >, <, >=, <=, ?)

Data Types

  • JavaScript has primitive data types (Boolean, Null, Undefined, Number, String etc.) and objects

Conditional Statements

  • JavaScript uses if…else and switch statements for conditional execution

Example 1: test1js.html

  • A basic example showing how to add JavaScript to an HTML file
  • Provides an alert box upon page load

Example 2: test1js_onload.html

  • Another example, with a similar function trigger when the page loads

Example 3: test1js_tab.html

  • A tab-based example using JavaScript to display tabs

Example...

  • Additional JavaScript examples (e.g., image changing)

JavaScript Add Two Numbers

  • Example using a form and textboxes to add numbers
  • Explanation of the JavaScript code and the result

JavaScript Fahrenheit to Celsius

  • Example converting Fahrenheit to Celsius using input and button

More...

  • Reference to more advanced JavaScript topics in a PDF format

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