Written by Sümeyye Sever (notes I took while creating web development projects)

The main difference between map and forEach is that map returns a new array with the results of the function applied to each element, while forEach does not return anything. Both map and forEach can modify the original array if the callback function modifies its elements.

//.map() function

const numbers = [1, 4, 9];
const roots = numbers.map((num)=> Math.sqrt(num));

//roots is now [1, 2, 3]
//numbers is still [1, 4, 9]

//.forEach() function

const numbers = [1, 4, 9];
const roots = [];

numbers.forEach((num) => {
	roots.push(Math.sqrt(num));
});

//roots is now [1, 2, 3]
//numbers is still [1, 4, 9]

//.filter() function

const words = ["python", "javascript", "java", "typescript", "c"];
const filteredWords = words.filter((word) => word.length > 6 );

//filteredWords is now ["javascript", "typescript"]