JavaScript - count number of true elements in array of boolean values

You can use filter() method to get array of all the truthy values from the original array, then the length property of the filtered array will be the number of truthy values.

Practical examples

Example 1

// ONLINE-RUNNER:browser;

const array = [true, false, true, true];

const result = array.filter(Boolean).length;

console.log(result); // 3

Example 2

// ONLINE-RUNNER:browser;

var array = [true, false, true, true];

const result = array.filter((element) => element).length;

console.log(result); // 3

See also

1. JavaScript - count occurrences of array elements

References

1. Array.prototype.filter() - JavaScript | MDN
2. Boolean() constructor - JavaScript | MDN