javascript count the digits in a number function problem

Question

I'm trying to count the digits of a number and I found this function

function countDigits(y){
  num = parseInt(y)
  count = 0
  if (num >= 1)
    ++count;

  while (num / 10 >= 1) {
    num /= 10;
    ++count;
  }
  
  return count;
}

console.log(countDigits("123456"));
console.log(countDigits("1"));
console.log(countDigits("012"));

I'm taking the input from a string digit y.

The problem with the function is when a number starts with a zero it doesn't count it?

Numbers can't start with a 0 (not including numbers between -1 and 1) — Nick is tired
– Nick is tired, Commented Feb 22, 2021 at 5:39
y is a string and I have to validate a phone number that is why I need the zero to be counted — beans
– beans, Commented Feb 22, 2021 at 5:40
@beans in that case, why not just get the length of the string (y.length)? — Nick is tired
– Nick is tired, Commented Feb 22, 2021 at 5:45

Not A Robot · Accepted Answer · 2021-02-22 05:45:54Z

4

parseInt will ignore leading zeroes. You need something like:

function countDigitsInANumericString(numeric) {
  return numeric.split('').filter((n) => Number.isFinite(parseInt(n))).length;
}

console.log(countDigitsInANumericString('0a1023')); // 5

console.log(countDigitsInANumericString('0123')); // 4

console.log(countDigitsInANumericString('123456')); // 6

edited Feb 22, 2021 at 5:45

Not A Robot

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answered Feb 22, 2021 at 5:42

Bill Sourour

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3 Comments

beans Over a year ago

It worked but I needed it without any string I should've made that clearer, thank you though

Bill Sourour Over a year ago

@gorak as of ES2015 it's probably better to use Number.isNaN to avoid some edge cases with the global isNaN function. But yes... that's a good alternative.

Bill Sourour Over a year ago

For anyone curious, the difference between Number.isNaN and Number.isFinite is that Number.isNaN(Number.Infitiy) returns false. In this case, it's hard to see how you end up with an infinite value so both would work.

Not A Robot · Accepted Answer · 2021-02-22 08:54:05Z

1

I updated your above function to count the 0s at the beginning of your number string. Though there can be other ways too.

var y = '000102';
var num = parseInt(y);
var count = 0;

while (y[count] == '0') {
  ++count;
}
if (num >= 1) {
  ++count;
}

while (num / 10 >= 1) {
  num /= 10;
  ++count;
}

console.log(count);

edited Feb 22, 2021 at 8:54

Not A Robot

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answered Feb 22, 2021 at 5:44

Beshambher Chaukhwan

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