how to make an array count up javascript code example

Example 1: create range array javascript

[...Array(10).keys()]
//=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Example 2: generate array range

for (i of range(1, 5)) {
    console.log(i);
}
/* Output
 * 1 2 3 4 5 */

[...range(1, 5)] // [1, 2, 3, 4, 5]

Example 3: count number of each element in array javascript

var arr = [5, 5, 5, 2, 2, 2, 2, 2, 9, 4];
var counts = {};

for (var i = 0; i < arr.length; i++) {
  var num = arr[i];
  counts[num] ? counts[num] + 1 : 1;
}

console.log(counts[5], counts[2], counts[9], counts[4]);