JavaScript Day 11 — Mastering JavaScript Basics: A Comprehensive Guide for Interview Preparation

100 Days of JavaScript Interview Prep: A Beginner’s Journey

Welcome to Day 11–100 Days of JavaScript Interview Prep: A Beginner’s Journey

Embarking on a 100-day adventure focused on learning, practice, and growth sounds like an incredibly rewarding journey.

DAY 11 (April 2nd, 2024) — Function Declaration and Function Expression in JavaScript with examples

Explain the difference between function declarations and function expressions in JavaScript.

Answer :

Function Declarations:

• Function declarations are defined using the function keyword followed by the function name and a block of code enclosed in curly braces.

function sayName() {
    console.log("Hello!");
}
console.log(sayName()) // can access 

• These functions are hoisted, it means they are available for use anywhere within their scope, even before the declaration.

console.log(sayName()) // can access even before declaration
function sayName() {
    console.log("Hello!");
}

Function expressions

Function expressions involve defining a function as part of an expression, typically by assigning it to a variable.

• Function expressions are not hoisted in the same way as function declarations, so they cannot be invoked before they are defined.

console.log(myName()) // can't access before decalaration
const myName =function sayName() {
    console.log("Hello!");
}

• These functions may or may not have a name, and if they do, they are only accessible within their containing scope.

Conclusion

• Function declarations are hoisted, while function expressions are not.
• Function declarations can be accessed anywhere within their containing scope, whereas function expressions can only be accessed after they have been defined.
• Function declarations require a name, while function expressions may or may not have a name (anonymous or named)

Examples below anonymous and named

//anonymous
const add = function(x, y) {
    return x + y;
};

named
const addTwo = function sum(x, y) {
    return x + y;
};

Happy Coding and Stay Tuned :)

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