Add .00 (toFixed) only if number has less than two decimal places

Question

I need to add zeroes, so that each number has at least two decimals, but without rounding. So for example:

5      --> 5.00
5.1    --> 5.10
5.11   --> 5.11 (no change)
5.111  --> 5.111 (no change)
5.1111 -->  5.1111  (no change) 

My function is missing an IF to check for less than two decimal places:

function addZeroes( num ) {
   var num = Number(num);
   if ( //idk ) {
      num = num.toFixed(2);
   }
   return num;
}

Thanks!

Posting an alternative answer, in addition to the two below. (Keep in mind that I'm no expert and this is just for text inputs, not for parsing complex values like colors that could have floating point issues, etc.)

function addZeroes( value ) {
    //set everything to at least two decimals; removs 3+ zero decimasl, keep non-zero decimals
    var new_value = value*1; //removes trailing zeros
    new_value = new_value+''; //casts it to string

    pos = new_value.indexOf('.');
    if (pos==-1) new_value = new_value + '.00';
    else {
        var integer = new_value.substring(0,pos);
        var decimals = new_value.substring(pos+1);
        while(decimals.length<2) decimals=decimals+'0';
        new_value = integer+'.'+decimals;
    }
    return new_value;
}

[This is not a duplicate question. The question you linked assumes "knowing that they have at least 1 decimal." Decimal points cannot be assumed in text inputs, and this was making errors.]

Answer 1

TL;DR:

num.toLocaleString("en", { minimumFractionDigits: 2 })

Fiddle

Other options:

If you are using optional chaining you can do it in one line like so:

const addZeroes = num => Number(num).toFixed(Math.max(num.split('.')[1]?.length, 2) || 2)

Fiddle

Without optional chaining you can do it like this:

function addZeroes(num) {
  const dec = num.split('.')[1]
  const len = dec && dec.length > 2 ? dec.length : 2
  return Number(num).toFixed(len)
}

Fiddle

Verbose method/explanation:

function addZeroes(num) {        
  var value = Number(num); // Convert input string to a number

  var parts = num.split("."); // Split the input string into two arrays

  // If there is no decimal point or not enough significant figures
  if(parts.length == 1 || parts[1].length < 3) { 
    value = value.toFixed(2); // Set the number to two decimal places
  }

  return value; // Return the value
}

// If you require the number as a string simply cast back as so
var num = String(value);

Fiddle