Description

The fill() method of Array instances changes all elements within a range of indices in an array to a static value. It returns the modified array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/fill

Example

const array1 = [1, 2, 3, 4];

// Fill with 0 from position 2 until position 4
console.log(array1.fill(0, 2, 4));
// Expected output: Array [1, 2, 0, 0]

// Fill with 5 from position 1
console.log(array1.fill(5, 1));
// Expected output: Array [1, 5, 5, 5]

console.log(array1.fill(6));
// Expected output: Array [6, 6, 6, 6]

Description

The pop() method of Array instances removes the last element from an array and returns that element. This method changes the length of the array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/pop

Example

const plants = ["broccoli", "cauliflower", "cabbage", "kale", "tomato"];
console.log(plants.pop());
// Expected output: "tomato"
console.log(plants);
// Expected output: Array ["broccoli", "cauliflower", "cabbage", "kale"]
plants.pop();
console.log(plants);
// Expected output: Array ["broccoli", "cauliflower", "cabbage"]

Description

The push() method of Array instances adds the specified elements to the end of an array and returns the new length of the array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push

Example

const animals = ["pigs", "goats", "sheep"];
const count = animals.push("cows");
console.log(count);
// Expected output: 4 console.log(animals);
// Expected output: Array ["pigs", "goats", "sheep", "cows"]
animals.push("chickens", "cats", "dogs");
console.log(animals);
// Expected output: Array ["pigs", "goats", "sheep", "cows", "chickens", "cats", "dogs"]

Description

The reverse() method of Array instances reverses an array in place and returns the reference to the same array, the first array element now becoming the last, and the last array element becoming the first. In other words, elements order in the array will be turned towards the direction opposite to that previously stated.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reverse

Example

const array1 = ["one", "two", "three"];
console.log("array1:", array1);
// Expected output: "array1:" Array ["one", "two", "three"]
const reversed = array1.reverse();
console.log("reversed:", reversed);
// Expected output: "reversed:" Array ["three", "two", "one"]
// Careful: reverse is destructive -- it changes the original array.
console.log("array1:", array1);
// Expected output: "array1:" Array ["three", "two", "one"]

Description

The shift() method of Array instances removes the first element from an array and returns that removed element. This method changes the length of the array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/shift

Example

const array1 = [1, 2, 3];
const firstElement = array1.shift();
console.log(array1);
// Expected output: Array [2, 3]
console.log(firstElement);
// Expected output: 1

Description

The sort() method of Array instances sorts the elements of an array in place and returns the reference to the same array, now sorted. The default sort order is ascending, built upon converting the elements into strings, then comparing their sequences of UTF-16 code units values.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort

Example

const months = ["March", "Jan", "Feb", "Dec"];
months.sort();
console.log(months);
// Expected output: Array ["Dec", "Feb", "Jan", "March"]

const array1 = [1, 30, 4, 21, 100000];
array1.sort();
console.log(array1);
// Expected output: Array [1, 100000, 21, 30, 4]

Description

The splice() method of Array instances changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice

Example

const months = ["Jan", "March", "April", "June"];
months.splice(1, 0, "Feb");
// Inserts at index 1
console.log(months);
// Expected output: Array ["Jan", "Feb", "March", "April", "June"]

months.splice(4, 1, "May");
// Replaces 1 element at index 4
console.log(months);
// Expected output: Array ["Jan", "Feb", "March", "April", "May"]

Description

The unshift() method of Array instances adds the specified elements to the beginning of an array and returns the new length of the array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/unshift

Example

const array1 = [1, 2, 3];
console.log(array1.unshift(4, 5));
// Expected output: 5
console.log(array1);
// Expected output: Array [4, 5, 1, 2, 3]