Methods for working with arrays in JavaScript

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  • push() – adds an element to the end of an array
  • pop() – removes the last element from an array
  • shift() – removes the first element from an array
  • unshift() – adds an element to the beginning of an array
  • splice() – adds or removes elements from an array at a specified index
  • slice() – returns a new array with a subset of elements from an original array
  • concat() – combines two or more arrays into a new array
  • forEach() – runs a function on each element of an array
  • map() – creates a new array with the results of a function applied to each element of an original array
  • filter() – creates a new array with elements that pass a test implemented by a provided function
  • reduce() – applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.
  • sort() – sorts the elements of an array in ascending or descending order.
  • It’s worth noting that many of these methods modify the original array, while others return a new array.
  1. push() – adds an element to the end of an array
let fruits = ["apple", "banana"];
fruits.push("orange");
console.log(fruits); // ["apple", "banana", "orange"]
  1. pop() – removes the last element from an array
let fruits = ["apple", "banana", "orange"];
fruits.pop();
console.log(fruits); // ["apple", "banana"]
  1. shift() – removes the first element from an array
let fruits = ["apple", "banana", "orange"];
fruits.shift();
console.log(fruits); // ["banana", "orange"]
  1. unshift() – adds an element to the beginning of an array
let fruits = ["banana", "orange"];
fruits.unshift("apple");
console.log(fruits); // ["apple", "banana", "orange"]
  1. splice() – adds or removes elements from an array at a specified index
let fruits = ["apple", "banana", "orange", "mango"];
fruits.splice(2, 1, "lemon", "kiwi");
console.log(fruits); // ["apple", "banana", "lemon", "kiwi", "mango"]
  1. slice() – returns a new array with a subset of elements from an original array
let fruits = ["apple", "banana", "orange", "mango"];
let citrus = fruits.slice(2);
console.log(citrus); // ["orange", "mango"]
  1. concat() – combines two or more arrays into a new array
let fruits = ["apple", "banana"];
let vegetables = ["carrot", "potato"];
let food = fruits.concat(vegetables);
console.log(food); // ["apple", "banana", "carrot", "potato"]
  1. forEach() – runs a function on each element of an array
let fruits = ["apple", "banana", "orange"];
fruits.forEach(fruit => console.log(fruit));
// apple
// banana
// orange
  1. map() – creates a new array with the results of a function applied to each element of an original array
let fruits = ["apple", "banana", "orange"];
let upperCaseFruits = fruits.map(fruit => fruit.toUpperCase());
console.log(upperCaseFruits); // ["APPLE", "BANANA", "ORANGE"]
  1. filter() – creates a new array with elements that pass a test implemented by a provided function
let fruits = ["apple", "banana", "orange", "mango"];
let longFruits = fruits.filter(fruit => fruit.length > 5);
console.log(longFruits); // ["banana", "orange"]
  1. reduce() – applies a function
let numbers = [1, 2, 3, 4, 5];
let sum = numbers.reduce((acc, curr) => acc + curr, 0);
console.log(sum); // 15
  1. sort() – sorts the elements of an array in ascending or descending order.
let fruits = ["orange", "apple", "banana"];
fruits.sort();
console.log(fruits); // ["apple", "banana", "orange"]

You can also sort an array of object by providing a comparator function

let people = [  { name: "Alice", age: 30 },  { name: "Bob", age: 25 },  { name: "Charlie", age: 35 }];

people.sort((a, b) => a.age - b.age);
console.log(people); 
// [{ name: "Bob", age: 25 },{ name: "Alice", age: 30 },{ name: "Charlie", age: 35 }]

Please note that sort() method sorts the elements of an array in ascending order by default, so if you want to sort it in descending order you need to provide a comparator function.

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