I want to Split a number into its digit (for example 4563 to 4 , 5 , 6 , 3 ) then addiction this digits. (for example: 4+5+6+3=18)

I can write code for 3 digit or 2 digit and ... numbers seperately but I cant write a global code for each number.

so this is my code for 2 digit numbers:

var a = 23
var b = Math.floor(a/10); // 2
var c = a-b*10; // 3
var total = b+c; // 2+3
console.log(total); // 5

and this is my code for 3 digit numbers:

var a = 456
var b = Math.floor(a/100); // 4
var c = a-b*100; // 56
var d = Math.floor(c/10); // 5
var e = c-d*10; // 6
var total = b+d+e; // 4+5+6
console.log(total); // 15

but I cant write a code to work with each number.How can I write a global code for each number?

I want to Split a number into its digit (for example 4563 to 4 , 5 , 6 , 3 ) then addiction this digits. (for example: 4+5+6+3=18)

I can write code for 3 digit or 2 digit and ... numbers seperately but I cant write a global code for each number.

so this is my code for 2 digit numbers:

var a = 23
var b = Math.floor(a/10); // 2
var c = a-b*10; // 3
var total = b+c; // 2+3
console.log(total); // 5

and this is my code for 3 digit numbers:

var a = 456
var b = Math.floor(a/100); // 4
var c = a-b*100; // 56
var d = Math.floor(c/10); // 5
var e = c-d*10; // 6
var total = b+d+e; // 4+5+6
console.log(total); // 15

but I cant write a code to work with each number.How can I write a global code for each number?

• javascript

• 2 stackoverflow./questions/9138064/… – BeNdErR Commented May 4, 2015 at 8:41
• 1 I guess stackoverflow./a/7784630/3894168 is what you want. – Zee Commented May 4, 2015 at 8:44

9 Answers 9

In modern browsers you can do an array operation like

var num = 4563;
var sum = ('' + num).split('').reduce(function (sum, val) {
    return sum + +val
}, 0)

Demo: Fiddle

where you first create an array digits then use reduce to sum up the values in the array

var num = 4563;
var sum = 0;
while(num > 0) {
  sum += num % 10;
  num = Math.floor(num / 10);
}
console.log(sum);

Do number%10(modulus) and then number/10(divide) till the number is not 0

I hope the following example is useful to you:

var text="12345";
var total=0;
for (i=0;i<text.length;i++)
{
  total+= parseInt(text[i]);
}    
alert(total);

This solution converts the number to string, splits it into characters and process them in the callback function (prev is the result from the previous call, current is the current element):

var a = 456;
var sum = a.toString().split("").reduce(function(prev, current){
    return parseInt(prev) + parseInt(current)
})

Here is how I would approach the problem. The trick I used was to split on the empty string to convert the string to an array and then use reduce on the array.

function digitSum(n) {
    // changes the number to a string and splits it into an array
    return n.toString().split('').reduce(function(result, b){
        return result + parseInt(b);
    }, 0);
}

As mentioned by several other posters (hat tip to my menter), there are several other good answers to this question as well.

Here is my solution using ES6 arrow functions as call back. - Convert the number into a string. - Split the string into an array. - Call the map method on that array. - Callback function parse each digit to an array.

let number = 65535;

//USING MAP TO RETURN AN ARRAY TO DIGITS
let digits = number.toString()
                    .split("")
                    .map(num => parseInt(num));
//OUTPUT TO DOM
digits.forEach(
  digit => 
  document.querySelector("#out").innerHTML += digit + "<br>"
);

<p id="out"></p>

1) You can cast input number to string, using .toString() method and expand it into array with spread (...) operator

const splitNumber = n => [ ...n.toString() ]

2) Another short way - using recursion-based solution like:

const splitNumber = n => n ? [ ...splitNumber(n/10|0), n%10 ] : []

<div style="text-align:center; margin:auto;">
This script limits the number of characters in the INPUT field to those specified in the QUANT field.
<form>
<input name="" type="number" id="quant" value = "" style="padding:6px; margin:0.8em;" /><br />
<input name="" type="number" id="input" oninput="calc()" style="padding:6px;  margin:0.8em;" /><br />
<input type="reset" style="width:150px;padding:8px; margin:0.8em;">
</form>
<div id="digit"></div><br />
<script>
let input;
let out = '';
let total = '';
let quant = "";

function calc(){
  quant = document.getElementById('quant').value;
  input = document.getElementById('input').value;
  total = input.split('');
  if(total.length > quant){
      document.getElementById('input').value = "";
      for(i=0; i < quant; i++){
          document.getElementById('input').value += total[i];
      }
}
out = total.length - 1;
if(out < 0){
   out = 0;
}
document.getElementById('digit').innerText = "Quantity: " + out;
}
</script>