Convert float to string with at least one decimal place (javascript)

Question

Let me give you an example.

var a = 2.0;
var stringA = "" + a;

I will get: stringA = "2", but I want: stringA = "2.0".

I don't want to lose precision however, so if:

var b = 2.412;
var stringB = "" + b;

I want to get the standard: stringB = "2.412".

That's why toFixed() won't work here. Is there any other way to do it, than to explicitly check for whole numbers like this?:

if (a % 1 === 0)
    return "" + a + ".0";
else
    return "" + a;

Answer 1

There is a built-in function for this.

var a = 2;
var b = a.toFixed(1);

This rounds the number to one decimal place, and displays it with that one decimal place, even if it's zero.

Answer 2

If you want to append .0 to output from a Number to String conversion and keep precision for non-integers, just test for an integer and treat it specially.

function toNumberString(num) { 
  if (Number.isInteger(num)) { 
    return num + ".0"
  } else {
    return num.toString(); 
  }
}

Input  Output
3      "3.0"
3.4567 "3.4567"