How do I separate an integer into separate digits in an array in JavaScript?

Question

This is my code so far:

var n = 123456789;
var d = n.toString().length;
var digits = [];
var squaredDigits = [];
for (i = d; i >= 1; i--) {
    var j = k / 10;
    var r = (n % k / j) - 0.5;
    var k = Math.pow(10, i);
    var result = r.toFixed(); 
    digits.push(result);
}

console.log(digits);

But when I run my code I get this: [9, 1, 2, 3, 4, 5, 6, 7, 8]

If anyone can see the problem or find a better solution I would very much appreciate it!

Answer 1

split, then looped over to square

here the numbers are split, then squared.

const n = 123456;
const numArr = Array.from(n.toString());

for (let i = 0; i < numArr.length; i++) {
  numArr[i] = `${numArr[i]**2}`;
}

console.log(numArr);

Answer 2

This is actually the cleanest solution I think.

  var n =  123456789;
  const digits = (`${n}`).split('')

You put it in a string literal but it is kept as numbers, and then it is split to an array and assigned to digits.

Answer 3

Assuming the value n:

const n = 123456789

A minimal ES6 version if you'd like:

String(n).split("").map(Number)

An even shorter but less readable version:

[...String(n)].map(Number)

Want to go even shorter (but less readable)?

[...`${n}`].map(Number)

Shorter you say (and basically illegible)!?

[...""+n].map(Number)

Now you're a real programmer, congrats!

Side note

These aren't really efficient (as most in this thread) since you're allocating 2 arrays instead of 1. Want to be more efficient? Try this which only allocates one array:

var arr = []
var str = String(n)
for (var i = 0; i < str.length; i++) {
  arr.push(Number(str[i]))
}

Oldschool but more efficient, huzzah!

Answer 4

var n = 38679;
var digits = n.toString().split("");
console.log(digits);

Now the number n is divided to its digits and they are presented in an array, and each element of that array is in string format. To transform them to number format do this:

var digitsNum = digits.map(Number);
console.log(digitsNum);

Or get an array with all elements in number format from the beginning:

var n = 38679;
var digits = n.toString().split("").map(Number);
console.log(digits);

Answer 5

Suppose,

let a = 123456

First we will convert it into string and then apply split to convert it into array of characters and then map over it to convert the array to integer.

let b = a.toString().split('').map(val=>parseInt(val))
console.log(b)

Answer 6

Update with string interpolation in ES2015.

const num = 07734;
let numStringArr = `${num}`.split('').map(el => parseInt(el)); // [0, 7, 7, 3, 4]

Answer 7

You can get a list of string from your number, by converting it to a string, and then splitting it with an empty string. The result will be an array of strings, each containing a digit:

const num = 124124124
const strArr = `${num}`.split("")

OR to build on this, map each string digit and convert them to a Number:

const intArr = `${num}`.split("").map(x => Number(x))

Answer 8

It is pretty short using Array destructuring and String templates:

const n = 12345678;
const digits = [...`${n}`];
console.log(digits);

Answer 9

let input = 12345664
const output = []
while (input !== 0) {
  const roundedInput = Math.floor(input / 10)
  output.push(input - roundedInput * 10)
  input = roundedInput
}
console.log(output)

Answer 10

const number = 1435;
number.toString().split('').map(el=>parseInt(el));

Answer 11

This will work for a number greater than 0. You don't need to convert the number into string:

function convertNumberToDigitArray(number) {
    const arr = [];
    while (number > 0) {
        let lastDigit = number % 10;
        arr.push(lastDigit);
        number = Math.floor(number / 10);
    }
    return arr;
}

Answer 12

It's very simple, first convert the number to string using the toString() method in JavaScript and then use split() method to convert the string to an array of individual characters.

For example, the number is num, then

const numberDigits = num.toString().split('');

Answer 13

I ended up solving it as follows:

const n = 123456789;
let toIntArray = (n) => ([...n + ""].map(Number));
console.log(toIntArray(n));

Answer 14

const toIntArray = (n) => ([...n + ""].map(v => +v))

Answer 15

Another method here. Since number in Javascript is not splittable by default, you need to convert the number into a string first.

var n = 123;
n.toString().split('').map(Number);

Answer 16

Modified the above answer a little bit. We don't really have to call the 'map' method explicitly, because it is already built-in into the 'Array.from' as a second argument. As of MDN.

Array.from(arrayLike[, mapFn[, thisArg]])

let num = 1234;
let arr = Array.from(String(num), Number);
console.log(arr); // [1, 2, 3, 4]

Answer 17

Here's an alternative to Nicolás Fantone's answer. You could argue it's maybe a little less readable. The emphasis is that Array.from() can take an optional map function as a parameter. There are some performance gains this way since no intermediate array gets created.

const n = 123456;
Array.from(n.toString(), (val) => Number(val)); // [1, 2, 3, 4, 5, 6]

Answer 18

It's been a 5+ years for this question but heay always welcome to the efficient ways of coding/scripting.

var n = 123456789;
var arrayN = (`${n}`).split("").map(e => parseInt(e))

Answer 19

const toIntArray = (n) => ([...n + ""].map(v => +v))

Answer 20

var num = 123456789;
num = num.toString(); //'123456789'
var digits = num.split(""); //[ '1', '2', '3', '4', '5', '6', '7', '8', '9' ]

Answer 21

What about:

const n = 123456;
Array.from(n.toString()).map(Number);
// [1, 2, 3, 4, 5, 6]

Answer 22

I realize this was asked several months ago, but I have an addition to samccone's answer which is more succinct but I don't have the rep to add as a comment!

Instead of:

(123456789).toString(10).split("").map(function(t){return parseInt(t)})

Consider:

(123456789).toString(10).split("").map(Number)

Answer 23

Move:

var k = Math.pow(10, i);

above

var j = k / 10;

Answer 24

(123456789).toString(10).split("")

^^ this will return an array of strings

(123456789).toString(10).split("").map(function(t){return parseInt(t)})

^^ this will return an array of ints

Answer 25

Why not just do this?

var n =  123456789;
var digits = (""+n).split("");