I'm trying to complete this kata. Trying to figure it out, I've seen this thread but I think I'm doing it as it says in there.

What am I doing wrong? Why doesn't it sort the numbers in descending order? This is my code so far:

function descendingOrder(n){
  let newN = n.toString().split(' ').sort(function(a,b){return b-a}).join();
  return parseInt(newN);
}

Test Passed: Value == 0 Test Passed: Value == 1 Expected: 987654321, instead got: 123456789

Thanks in advance

I'm trying to complete this kata. Trying to figure it out, I've seen this thread but I think I'm doing it as it says in there.

What am I doing wrong? Why doesn't it sort the numbers in descending order? This is my code so far:

function descendingOrder(n){
  let newN = n.toString().split(' ').sort(function(a,b){return b-a}).join();
  return parseInt(newN);
}

Test Passed: Value == 0 Test Passed: Value == 1 Expected: 987654321, instead got: 123456789

Thanks in advance

• javascript
• sorting

• I suggest splitting your variable assignment into several lines. Assign each intermediate step to a variable and print the value of the variable. Use console.log(). For more debugging tips, see this blog article. – Code-Apprentice Commented Apr 1, 2018 at 20:49
• n.toString().split('').sort(function(a,b){return b-a}).join(''); – Ele Commented Apr 1, 2018 at 20:49

4 Answers 4

You need to split the string with an empty string '' to get single digits and join it with an empty string.

Splitting with a character which is not part of the string results in an array with a single value. A later joined array returns this single element. That is why you get the same value as result as the input.

Array#join without a specified separator, returns a comma separated string with the values.

let newN = n.toString().split('').sort(function (a, b) { return b - a; }).join('');

At the end, you could take an unary plus +, like

return +newN;

for getting an numerical value.

BTW, with the use of parseInt, you may specify a radix, because strings with leading zero may be converted to an octal number.

Here is an explained answer

function descendingOrder(n) {
  let result = n
    .toString() // convert numbers to string
    .split('') // split each string char in to an array of chars
    .sort((a, b) => b - a) // sort that array descending
    .join('') // regroup all items in that array into 1 string

  return parseInt(result) // turn the group of strings into an array
}

function descendingOrder(n){
  return +('' + n).split('').sort().reverse().join('');
}

Like the other answers have already stated you will need to call split with an empty string to properly create an array containing each character.

Also, when I tested join() I noticed commas in the output (chrome 65). I added a replace function to strip the commas, which passed the test.

function descendingOrder(n){
  let newN = n.toString().split('').sort(function(a,b){return b-a}).join().replace(/,/g,'');
  return parseInt(newN);
}