Format a javascript number with a Metric Prefix like 1.5K, 1M, 1G, etc [duplicate]

Question

I want to display numbers using a Metric Prefix with 3 significant digits like so:

1 shows as 1
999 shows as 999
1000 shows as 1K
999000 shows as 999K
1000000 shows as 1M
1500000 shows as 1.5M
1000000000 shows as 1G
etc...

I could write my own javascript function to do this but I was wondering if there is a standard way of formatting numbers like this?

Answer 1

You can put the ranges in an array of objects, and just loop through it to format the number:

var ranges = [
  { divider: 1e18 , suffix: 'E' },
  { divider: 1e15 , suffix: 'P' },
  { divider: 1e12 , suffix: 'T' },
  { divider: 1e9 , suffix: 'G' },
  { divider: 1e6 , suffix: 'M' },
  { divider: 1e3 , suffix: 'k' }
];

function formatNumber(n) {
  for (var i = 0; i < ranges.length; i++) {
    if (n >= ranges[i].divider) {
      return (n / ranges[i].divider).toString() + ranges[i].suffix;
    }
  }
  return n.toString();
}

Usage example:

var s = formatNumber(999000);

To also handle negative numbers, you would add this first in the function:

  if (n < 0) {
    return '-' + formatNumber(-n);
  }