Convert long number into abbreviated string in JavaScript, with a special shortness requirement

Question

In JavaScript, how would one write a function that converts a given [edit: positive integer] number (below 100 billion) into a 3-letter abbreviation -- where 0-9 an

Answer 1

The modern, easy, built-in, highly customizable, and 'no-code' way: Intl.FormatNumber 's format function (compatibility graph)

var numbers = [98721, 9812730,37462,29,093484620123, 9732,0283737718234712]
for(let num of numbers){
  console.log(new Intl.NumberFormat( 'en-US', { maximumFractionDigits: 1,notation: "compact" , compactDisplay: "short" }).format(num));
}
98.7K
9.8M
37.5K
29
93.5B
9.7K
283.7T

Notes:

• If you're using typescript add a //@ts-ignore before notation (source)
• And a list of all the keys in the options parameter: https://docs.w3cub.com/javascript/global_objects/numberformat/
• When using style: 'currency', you must remove maximumFractionDigits, as it will figure this out for you.

Answer 2

I believe ninjagecko's solution doesn't quite conform with the standard you wanted. The following function does:

function intToString (value) {
    var suffixes = ["", "k", "m", "b","t"];
    var suffixNum = Math.floor((""+value).length/3);
    var shortValue = parseFloat((suffixNum != 0 ? (value / Math.pow(1000,suffixNum)) : value).toPrecision(2));
    if (shortValue % 1 != 0) {
        shortValue = shortValue.toFixed(1);
    }
    return shortValue+suffixes[suffixNum];
}

For values greater than 99 trillion no letter will be added, which can be easily fixed by appending to the 'suffixes' array.

Edit by Philipp follows: With the following changes it fits with all requirements perfectly!

function abbreviateNumber(value) {
    var newValue = value;
    if (value >= 1000) {
        var suffixes = ["", "k", "m", "b","t"];
        var suffixNum = Math.floor( (""+value).length/3 );
        var shortValue = '';
        for (var precision = 2; precision >= 1; precision--) {
            shortValue = parseFloat( (suffixNum != 0 ? (value / Math.pow(1000,suffixNum) ) : value).toPrecision(precision));
            var dotLessShortValue = (shortValue + '').replace(/[^a-zA-Z 0-9]+/g,'');
            if (dotLessShortValue.length <= 2) { break; }
        }
        if (shortValue % 1 != 0)  shortValue = shortValue.toFixed(1);
        newValue = shortValue+suffixes[suffixNum];
    }
    return newValue;
}

Answer 3

Here's another take on it. I wanted 123456 to be 123.4K instead of 0.1M

function convert(value) {

    var length = (value + '').length,
        index = Math.ceil((length - 3) / 3),
        suffix = ['K', 'M', 'G', 'T'];

    if (length < 4) return value;
    
    return (value / Math.pow(1000, index))
           .toFixed(1)
           .replace(/\.0$/, '') + suffix[index - 1];

}

var tests = [1234, 7890, 123456, 567890, 800001, 2000000, 20000000, 201234567, 801234567, 1201234567];
for (var i in tests)
    document.writeln('<p>convert(' + tests[i] + ') = ' + convert(tests[i]) + '</p>');

Answer 4

@nimesaram

Your solution will not be desirable for the following case:

Input 50000
Output 50.0k

---

Following solution will work fine.

const convertNumberToShortString = (
  number: number,
  fraction: number
) => {
  let newValue: string = number.toString();
  if (number >= 1000) {
    const ranges = [
      { divider: 1, suffix: '' },
      { divider: 1e3, suffix: 'k' },
      { divider: 1e6, suffix: 'm' },
      { divider: 1e9, suffix: 'b' },
      { divider: 1e12, suffix: 't' },
      { divider: 1e15, suffix: 'p' },
      { divider: 1e18, suffix: 'e' }
    ];
    //find index based on number of zeros
    const index = Math.floor(Math.abs(number).toString().length / 3);
    let numString = (number / ranges[index].divider).toFixed(fraction);
    numString =
      parseInt(numString.substring(numString.indexOf('.') + 1)) === 0
        ? Math.floor(number / ranges[index].divider).toString()
        : numString;
    newValue = numString + ranges[index].suffix;
  }
  return newValue;
};

// Input 50000
// Output 50k
// Input 4500
// Output 4.5k

Answer 5

Based on my answer at https://stackoverflow.com/a/10600491/711085 , your answer is actually slightly shorter to implement, by using .substring(0,3):

function format(n) {
    with (Math) {
        var base = floor(log(abs(n))/log(1000));
        var suffix = 'kmb'[base-1];
        return suffix ? String(n/pow(1000,base)).substring(0,3)+suffix : ''+n;
    }
}

(As usual, don't use Math unless you know exactly what you're doing; assigning var pow=... and the like would cause insane bugs. See link for a safer way to do this.)

> tests = [-1001, -1, 0, 1, 2.5, 999, 1234, 
           1234.5, 1000001, Math.pow(10,9), Math.pow(10,12)]
> tests.forEach(function(x){ console.log(x,format(x)) })

-1001 "-1.k"
-1 "-1"
0 "0"
1 "1"
2.5 "2.5"
999 "999"
1234 "1.2k"
1234.5 "1.2k"
1000001 "1.0m"
1000000000 "1b"
1000000000000 "1000000000000"

You will need to catch the case where the result is >=1 trillion, if your requirement for 3 chars is strict, else you risk creating corrupt data, which would be very bad.

Answer 6

After some playing around, this approach seems to meet the required criteria. Takes some inspiration from @chuckator's answer.

function abbreviateNumber(value) {

    if (value <= 1000) {
        return value.toString();
    }

    const numDigits = (""+value).length;
    const suffixIndex = Math.floor(numDigits / 3);

    const normalisedValue = value / Math.pow(1000, suffixIndex);

    let precision = 2;
    if (normalisedValue < 1) {
        precision = 1;
    }

    const suffixes = ["", "k", "m", "b","t"];
    return normalisedValue.toPrecision(precision) + suffixes[suffixIndex];
}