Introduction to JavaScript

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JavaScript is a dynamic programming language that’s used for web development, in web applications, for server-side development, and more. Initially, JavaScript was only used in web browsers, but now it has become widespread in server-side website deployments and for non-web environments as well. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

JavaScript is used to enhance user interfaces and improve website interactivity. For example, it can be used to create interactive maps, animated 2D and 3D graphics, comprehensive forms, and much more. It operates on the client’s computer and can interact with the user, control the browser, communicate asynchronously, and alter the document content that is displayed.

Tips:

  1. Use comments: They help you understand what your code is doing, can assist others who are reading your code, and remind you of what you were thinking when you wrote the code.
  2. Learn to debug: Understanding how to use browser developer tools to debug JavaScript can save you a lot of time.
  3. Keep code readable: Use meaningful variable names and keep your functions focused on a single task.
  4. Understand scope: JavaScript has function scope and uses lexical scoping. Understand how these work to avoid bugs.
  5. Practice regularly: JavaScript, like any language, requires practice. Try building small projects or solving programming challenges.

Coding Example:

Below is a simple example of a JavaScript function that calculates the sum of two numbers:

function addNumbers(a, b) { return a + b; } const sum = addNumbers(5, 10); console.log(sum); // Output: 15

Quiz Questions:

  1. What is JavaScript primarily used for in web development? a) Styling web pages b) Backend development c) Creating interactive web pages d) Storing data on the server
  2. Which of the following data types is NOT supported by JavaScript? a) Boolean b) Integer c) Undefined d) Symbol
  3. What does the following JavaScript code return: console.log("10" + 5);? a) 15 b) “105” c) TypeError d) “15”
  4. What method is used to write an internal JavaScript function in an HTML document? a) <js> b) <script> c) <java> d) <programming>
  5. What keyword is used to declare a block-scoped local variable in JavaScript? a) var b) let c) const d) block
  6. Which method is used to round a number to the nearest integer in JavaScript? a) Math.round() b) Math.floor() c) Math.ceil() d) Math.fix()
  7. How do you add a comment in JavaScript? a) <!–This is a comment–> b) // This is a comment c) /* This is a comment */ d) Both b and c are correct
  8. What will the following code output: console.log(typeof 42);? a) “number” b) “int” c) “float” d) “numeric”
  9. How do you create a function in JavaScript? a) function myFunction() b) create myFunction() c) function:myFunction() d) new Function()
  10. What is a typical use case for asynchronous JavaScript code? a) Changing a CSS style b) Writing to a file on the server c) Fetching data from a remote server d) Calculating mathematical functions