Finding The Smallest Increment Of A Number

Is there any built in capability in JavaScript that allows you to get the smallest increment of a certain number without expanding it? For example: var i = 0.0003412 smallest incre

Solution 1:

a different approach to parsing the value.

function smallestIncrement(nr) {
  if (nr < 0) nr = -nr;
  let str = nr.toExponential(),
    e = str.indexOf("e");

  return Number("1e" + (str.substr(e + 1) - Math.max(0, e - 2)));
}
//just for completeness
function biggestIncrement(nr) {
  if (nr < 0) nr = -nr;
  let str = nr.toExponential();
  return Number("1" + str.substr(str.indexOf("e")))
}

//floating point math has issues. like:
//0.1 + 0.2 === 0.30000000000000004
function fixFloat(v){
   return Math.round(v/1e-14)*1e-14;
}

[
  0.0003412,
  -3000,
  12.340,
  0.0000000123
].forEach(nr => {
  console.log(
    nr,
    fixFloat(nr+smallestIncrement(nr)),
    fixFloat(nr+biggestIncrement(nr))
  );
})

.as-console-wrapper {
  top: 0;
  max-height: 100%!important
}

you stated that for values without decimal places, you want the step to be 1.

I didn't add that into the functions since I don't see, how/why there should be a difference in logic between 1.234e-10 and 1.234e+10.
You can clamp this by performing a simple Math.min(1, smallestIncrement(nr)) or by changing the code to return Number("1e" + Math.min(0, str.substr(e + 1) - Math.max(0, e - 2)));

Solution 2:

There is no built in function for this, if that's your question. You would have to come up with a solution yourself. Something like this:

Math.pow(0.1, String(num).split('.')[1].length)