How to Get the Size of an Array in JavaScript

To get the size (or length) of an array in JavaScript, we can use array.length property. The size of array refers to the number of elements present in that array.

Syntax

const a = [ 10, 20, 30, 40, 50 ]
let s = a.length;  //  s => 5

The JavaScript Array Length returns an unsigned integer value that represents the number of elements present in the array. The value is non-negative and always a 32-bit integer.

// Defining an array
const a = [ 10, 20, 30, 40, 50 ] 

// Storing length of array
let l = a.length;

// Displaying the length of arr1
console.log("Length of the Array is:", l);

Length of the Array is: 5

Get the Size of an Array using array.reduce() Method

The reduce() method iterates over each element of an array, accumulating a value based on a callback function. To get the size of an array, reduce() increments an accumulator for each element, returning the final count.

Syntax

const size  = array.reduce((acc) => acc + 1, 0);

// Defining an array
const a = [ 10, 20, 30, 40, 50 ] 

// Iterating with initial value 0
const s = a.reduce((acc) => acc + 1, 0);  
console.log("The size of the given array is:", s); 

The size of the given array is: 5

Get the Size of an Array using for...of Loop

We can use the for...of loop to count elements manually by incrementing a counter.

const a = [1, 2, 3, 4, 5];
let c = 0;

for (let element of a) {
  	c++;
}

console.log(c);

5