JavaScript Array Methods
Basic Array Methods
Array length
Array toString()
Array at()
Array join()
Array pop()
Array push()
Array shift()
Array unshift()
Array isArray()
Array delete()
Array concat()
Array copyWithin()
Array flat()
Array slice()
Array splice()
Array toSpliced()
JavaScript Array length
The length property returns the length (size) of an array:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let size = fruits.length;
The length property can also be used to set the length of an array:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.length = 2;
JavaScript Array toString()
The toString() method returns the elements of an array as a comma separated string.
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let myList = fruits.toString();
Every JavaScript object has a toString() method.
The toString() method is used internally by JavaScript when an object needs to be displayed as a text (like in HTML), or when an object needs to be used as a string.
JavaScript Array at()
ES2022 introduced the array method at():
Examples
Get the third element of fruits using at():
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.at(2);
Get the third element of fruits using []:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits[2];
JavaScript Array join()
The join() method also joins all array elements into a string.
It behaves just like toString(), but in addition you can specify the separator:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.join(" * ");
Result:
Banana * Orange * Apple * Mango
Popping and Pushing
When you work with arrays, it is easy to remove elements and add new elements.
This is what popping and pushing is:
Popping items out of an array, or pushing items into an array.
JavaScript Array pop()
The pop() method removes the last element from an array:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.pop();
The pop() method returns the value that was "popped out":
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.pop();
JavaScript Array push()
The push() method adds a new element to an array (at the end):
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.push("Kiwi");
The push() method returns the new array length:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let length = fruits.push("Kiwi");
Shifting Elements
Shifting is equivalent to popping, but working on the first element instead of the last.
JavaScript Array shift()
The shift() method removes the first array element and "shifts" all other elements to a lower index.
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.shift();
The shift() method returns the value that was "shifted out":
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.shift();
JavaScript Array unshift()
The unshift() method adds a new element to an array (at the beginning), and "unshifts" older elements:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon");
The unshift() method returns the new array length:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon");
Changing Elements
Array elements are accessed using their index number:
Array indexes start with 0:
[0] is the first array element
[1] is the second
[2] is the third ...
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[0] = "Kiwi";
JavaScript Array length
The length property provides an easy way to append a new element to an array:
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[fruits.length] = "Kiwi";
