map filter chaining in javascript code example

Example 1: javascript factor chain

const factors = number => [...Array(number + 1).keys()].filter(i=>number % i === 0);
console.log(factors(36));      //  [1, 2, 3, 4, 6, 9, 12, 18, 36]

Example 2: javascript factor chain

function calculate(num) {
    var str = "0";
    for (var i = 1; i <= num; i++) {
        if (num % i == 0) {
            str += ',' + i;
        }
    }
    alert(str);
}

calculate(232);

Example 3: javascript factor chain

function factorChain(num) {
 let n = num.slice(num.length - 1, num.length)[0]
 return [...Array(n + 1).keys()]
	 .filter(v => n % v === 0)
	 .map((v, i) => v === num[i])[0]
}