mout/number/abbreviate.js

var enforcePrecision = require('./enforcePrecision');
    var _defaultDict = {
        thousand: "K",
        million: "M",
        billion: "B",
    };

    /**
     * Abbreviate number if bigger than 1000. (eg: 2.5K, 17.5M, 3.4B, ...)
     */
    function abbreviateNumber(val, nDecimals, dict) {
        nDecimals = nDecimals != null ? nDecimals : 1;
        dict = dict || _defaultDict;
        val = enforcePrecision(val, nDecimals);

        var str, mod;
        var negative = false;

        if (val < 0) {
            val = -val;
            negative = true;
        }

        if (val < 1000000) {
            mod = enforcePrecision(val / 1000, nDecimals);
            // might overflow to next scale during rounding
            str = mod < 1000 ? mod + dict.thousand : 1 + dict.million;
        } else if (val < 1000000000) {
            mod = enforcePrecision(val / 1000000, nDecimals);
            str = mod < 1000 ? mod + dict.million : 1 + dict.billion;
        } else {
            str = enforcePrecision(val / 1000000000, nDecimals) + dict.billion;
        }

        if (negative) {
            str = "-" + str;
        }

        return str;
    }

    module.exports = abbreviateNumber;