Get from one number an array of numbers without brackets

Question

Need to receive:

digitize(12345) -> [5,4,3,2,1]

I wrote a code:

function digitize(n) {
let arr = Array.from(n + '');
return arr.reverse();
}

console.log(digitize(12345));

Output: [ '5', '4', '3', '2', '1' ]

This is very close, but this is showing an array of strings. How can I get an array of numbers (without the quotes), instead?

Answer 1

You could map (the second parameter of Array.from) with Number.

This approach works only for positive integers which are equal or less than Number.MAX_SAFE_INTEGER (9007199254740991).

function digitize(n) {
    return Array
        .from(n.toString(), Number)
        .reverse();
}

console.log(digitize(12345));

Answer 2

You could consider a recursive function, and do it without conversion to string:

function digitize(n) {
    return n < 10 ? [n] : [n % 10, ...digitize(Math.floor(n / 10))];
}

console.log(digitize(12345));

Answer 3

I would not go the "hacky", buggy and presumably less efficient route over stringification here:

function digitize(n) {
    const digits = [];
    while (n >= 1) {
        digits.push(n % 10);
        n = Math.floor(n / 10);
    }
    return digits;
}

or using a do-while depending if you want digitize(0) to be [0] instead of []:

function digitize(n) {
    const digits = [];
    do {
        digits.push(n % 10);
        n = Math.floor(n / 10);
    } while (n >= 1)
    return digits;
}

this will still fail for some large floats due to precision issues though.

Answer 4

Try

// The following function would give you an array of numbers in descending order of the digits of a number given as an argument to the function

function digitize(n) {
 const str = n.toString();
 const myArr = str.split("");
 const reversedArr = myArr.map(function (x) { 
  return parseInt(x, 10); 
}).sort((a,b)=>{return b-a});
 return reversedArr
}

console.log(digitize(12345))
console.log(digitize(45343))
console.log(digitize(484643))

// [5, 4, 3, 2, 1]
// [5, 4, 4, 3, 3]
// [8, 6, 4, 4, 4, 3]

// The following function would give you an array of numbers in reversed order of the digits of a number given as an argument to the function

function digitize(n) {
 const str = n.toString();
 const myArr = str.split("");
 const reversedArr = myArr.map(function (x) { 
  return parseInt(x, 10); 
}).reverse();
 return reversedArr
}

console.log(digitize(12345));
console.log(digitize(45343));
console.log(digitize(484643));

// [5, 4, 3, 2, 1]
// [3, 4, 3, 5, 4]
// [3, 4, 6, 4, 8, 4]