Get the last digit of a decimal value in JavaScript

Question

Is there any function in JavaScript that will return the unit size of the least significant digit of a decimal number?

For example:

• if the number is 1.5, return 0.1

• if the number is 0.15, return 0.01

• if the number is 0.10, return 0.01 (yeah, that's right)

• if the number is 0.100, return 0.001

And for an integer value, just return 1.

For example:

• if the number is 15, return 1

• if the number is 150, return 1

• if the number is -32, return 1

Answer 1

Find the position of the period and compare it to the length of the string:

function smallestDecimalUnit(s) {
  var pos = s.indexOf('.');
  if (pos == -1) {
    return 1;
  }
  return Math.pow(10, pos - s.length + 1);
}

function test(s) {
  document.write(s + ' &rarr; ' + smallestDecimalUnit(s) + '<br><br>');
}

test('1.5');
test('0.15');
test('0.10');
test('15');
test('150');

body {
  font-family: sans-serif;
}