JavaScript Number Split into individual digits

You can also do it in the "mathematical" way without treating the number as a string:

var num = 278;
var digits = [];
while (num > 0) {
    digits.push(num % 10);
    num = Math.trunc(num / 10);
}
digits.reverse();
console.log(digits);

One upside I can see is that you won't have to run parseInt() on every digit, you're dealing with the actual digits as numeric values.

var num = 123456;
var digits = num.toString().split('');
var realDigits = digits.map(Number)
console.log(realDigits);

var number = 12354987,
    output = [],
    sNumber = number.toString();

for (var i = 0, len = sNumber.length; i < len; i += 1) {
    output.push(+sNumber.charAt(i));
}

console.log(output);

/* Outputs:
 *
 * [1, 2, 3, 5, 4, 9, 8, 7]
 */ 

UPDATE: Calculating a sum

for (var i = 0, sum = 0; i < output.length; sum += output[i++]);
console.log(sum);

/*
 * Outputs: 39
 */