ds-algo-study/DS-n-Algos/ALGO/callbacks-solution/problems/08-count.js

Just experimenting with publishing a package

/*******************************************************************************
Write a function `count` that accepts an array and a callback as arguments. The
function should return the number of elements of the array that return true when
passed to the callback.

Examples:

let result1 = count([18, 5, 32, 7, 100], function (n) {
    return n % 2 === 0;
});
console.log(result1); // 3

let result2 = count([17, 5, 31, 7, 100], function (n) {
    return n % 2 === 0;
});
console.log(result2); // 1

let result3 = count(['follow', 'the', 'yellow', 'brick', 'road'], function (str) {
    return str.includes('o');
});
console.log(result3); // 3

let result4 = count(['follow', 'the', 'yellow', 'brick', 'road'], function (str) {
    return str.includes('x');
});
console.log(result4); // 0
*******************************************************************************/

function count(array, cb) {
  let numTrue = 0;
  array.forEach(function(el) {
    if (cb(el)) {
      numTrue++;
    }
  });
  return numTrue;
}

//******************---------------------******************\\*/
module.exports = count;