JAVASCRIPT

initialize javascript array variable

var arrayName = new Array();
var arrayName = new Array(Number length);
var arrayName = new Array(element1, element2, element3);

javascript initialize array

const array = new Array(5).fill(0);

console.log(array);

// [0, 0, 0, 0, 0]

initialize array

    // designated initialization --> it's a way to initialize elements of an array by it's index,
    // and set the value of the other elements to 0

    // ex 1
    int arr[5] = {[2] = 5, [3] = 10};
    for (int i = 0; i < 5; i++)
    {
        printf("%d ", arr[i]); // 0 0 5 10 0
    }
	
	// ex 2
	int arr[10] = {1, 7, [2] = 5, [3] = 10};
	for(int i = 0;i<10;i++){
		printf("%d ", arr[i]); // 1 7 5 10 0 0 0 0 0 0
    }
	// ex 3
	int arr[ ] = {2, [5] = 1}; // size is 6
    printf("%lu", sizeof(arr)); // 24 --> 6 * 4

Declare and Initialize Arrays in javascript

const array = Array(5).fill(''); 
// Output 
(5) ["", "", "", "", ""]

const matrix = Array(5).fill(0).map(()=>Array(5).fill(0)); 
// Output
(5) [Array(5), Array(5), Array(5), Array(5), Array(5)]
0: (5) [0, 0, 0, 0, 0]
1: (5) [0, 0, 0, 0, 0]
2: (5) [0, 0, 0, 0, 0]
3: (5) [0, 0, 0, 0, 0]
4: (5) [0, 0, 0, 0, 0]
length: 5

how to initialize an array in javascript

var array_name = [item1, item2, ...];  

How to initialize an array

my @array = ();