Array.prototype.push()

Overview.

The Array.prototype.push() method adds one or more elements to the end of an array and returns the new length of the array.

Syntax

array.push(element1[, ...[, elementN]])
array.push(element1[, element2[, ...[, elementN]]])

Parameters

• element1: The first element to add to the array.
• elementN (optional): Additional elements to add to the end of the array.

return value

The new length of the array after the elements have been added.

Examples

const animals = ["dog", "cat"];
const newLength = animals.push("bird");
// animals is now ["dog", "cat", "bird"]
// newLength is 3

const animals2 = ["dog", "cat"];
animals2.push("bird", "fish");
// animals2 is now ["dog", "cat", "bird", "fish"]

Use cases

Adding Elements to an Array: The push() method is commonly used to add one or more elements to an array.

const fruits = ["apple", "banana"];
fruits.push("orange", "mango");
// fruits is now ['apple', 'banana', 'orange', 'mango']

Merging Arrays: The push() method can also be used to merge multiple arrays into one.

const array1 = [1, 2, 3];
const array2 = [4, 5, 6];
const array3 = [7, 8, 9];
const result = [];
result.push(...array1, ...array2, ...array3);
// result is now [1, 2, 3, 4, 5, 6, 7, 8, 9]

Implementing a Stack: The push() method can be used to implement a stack, which is a collection of elements that follows the Last-In-First-Out (LIFO) principle.

const stack = [];
stack.push("item 1");
stack.push("item 2");
stack.push("item 3");
console.log(stack.pop()); // "item 3"
console.log(stack.pop()); // "item 2"
console.log(stack.pop()); // "item 1"

Appending Multiple Arguments to a Function: The push() method can be used to append multiple arguments to a function call.

function sum(a, b, c) {
  return a + b + c;
}
const numbers = [1, 2, 3];
console.log(sum(...numbers)); // 6
numbers.push(4, 5, 6);
console.log(sum(...numbers)); // 15

Note: The push() method modifies the original array and returns the new length of the array after the elements have been added.

Notes

• The push() method modifies the original array.
• You can pass multiple elements as arguments to push().
• The return value of push() is the new length of the array after the elements have been added.
• The push() method can be used to append elements to the end of an array, similar to the concat() method. However, push() modifies the original array, while concat() returns a new array.