Introduction Function declarations and expressions
π Dive into the heart of JavaScript, where functions and methods reign supreme. This quiz is designed for everyone passionate about coding – from those taking their first steps in JavaScript to seasoned developers looking to brush up on their knowledge. π
Here’s a sneak peek of what’s in store:
- Do you know the ins and outs of function declarations and expressions?
- Can you navigate the nuances of arrow functions?
- Are you adept at understanding how ‘this’ keyword works in different contexts?
π No coding required in this quiz – just your sharp mind and enthusiasm. It’s a great opportunity to assess your understanding and maybe even learn something new along the way! π§
JavaScript Functions and Methods
JavaScript functions and methods are essential for organizing and reusing code. Functions allow you to define a block of code, call it, and execute it as many times as needed. Methods are functions that belong to an object.
1. Function Declaration
Example: Declaring a simple function
function greet(name) {
return `Hello, ${name}!`;
}
console.log(greet(‘Alice’)); // Output: “Hello, Alice!”
Explanation: This is a basic function declaration where greet is a function that takes one parameter, name, and returns a greeting message.
2. Function Expression
Example: Creating a function expression
const square = function(number) {
return number * number;
};
console.log(square(4)); // Output: 16
Explanation: A function expression assigns an anonymous function to a variable (square). This function can then be called using the variable name.
3. Arrow Functions
Example: Using an arrow function
const add = (a, b) => a + b;
console.log(add(2, 3)); // Output: 5
Explanation: Arrow functions provide a more concise syntax for writing functions. They are particularly useful for short functions and when using higher-order functions.
4. Methods in Objects
Example: Method in an object
const person = {
name: ‘Alice’,
greet: function() {
return `Hello, I’m ${this.name}`;
}
};
console.log(person.greet()); // Output: “Hello, I’m Alice”
Explanation: Methods are functions that are stored as object properties. In this example, greet is a method of the person object.
Quiz Questions and Answers
Q1: What is the difference between a function declaration and a function expression in JavaScript?
- A) Only a function declaration can have a name
- B) A function declaration is hoisted, but a function expression is not
- C) Function expressions cannot take parameters
Answer: B) A function declaration is hoisted, but a function expression is not
Q2: What is the primary use of arrow functions in JavaScript?
- A) To create methods in objects
- B) For shorter syntax and handling this differently
- C) To declare global functions
Answer: B) For shorter syntax and handling this differently
Q3: How do you call a function stored in a variable myFunc?
- A) myFunc;
- B) call myFunc;
- C) myFunc();
Answer: C) myFunc();
Q4: What will be the output of the following code?
function multiply(a, b) {
return a * b;
}
console.log(multiply(2, 3));
- A) 6
- B) “2 * 3”
- C) undefined
Answer: A) 6
Q5: In the context of a method, what does the keyword this refer to?
- A) The global object
- B) The function itself
- C) The object that the method is a part of
Answer: C) The object that the method is a part of
These examples and questions highlight the importance of understanding JavaScript functions and methods, crucial for organizing code and creating efficient, reusable scripts.