static makeFormatter()

in resources/perf.webkit.org/public/v3/models/metric.js [100:138]
15 lines of code
6 McCabe index (conditional complexity)

    static makeFormatter(unit, sigFig = 2, alwaysShowSign = false)
    {
        let isMiliseconds = false;
        if (unit == 'ms') {
            isMiliseconds = true;
            unit = 's';
        }

        if (!unit)
            return function (value) { return value.toFixed(2) + ' ' + (unit || ''); }

        var divisor = unit == 'B' ? 1024 : 1000;
        var suffix = ['\u03BC', 'm', '', 'K', 'M', 'G', 'T', 'P', 'E'];
        var threshold = sigFig >= 3 ? divisor : (divisor / 10);
        let formatter = function (value, maxAbsValue = 0) {
            var i;
            var sign = value >= 0 ? (alwaysShowSign ? '+' : '') : '-';
            value = Math.abs(value);
            let sigFigForValue = sigFig;

            // The number of sig-figs to reduce in order to match that of maxAbsValue
            // e.g. 0.5 instead of 0.50 when maxAbsValue is 2.
            let adjustment = 0;
            if (maxAbsValue && value)
                adjustment = Math.max(0, Math.floor(Math.log(maxAbsValue) / Math.log(10)) - Math.floor(Math.log(value) / Math.log(10)));

            for (i = isMiliseconds ? 1 : 2; value && value < 1 && i > 0; i--)
                value *= divisor;
            for (; value >= threshold; i++)
                value /= divisor;

            if (adjustment) // Make the adjustment only for decimal positions below 1.
                adjustment = Math.min(adjustment, Math.max(0, -Math.floor(Math.log(value) / Math.log(10))));

            return sign + value.toPrecision(sigFig - adjustment) + ' ' + suffix[i] + (unit || '');
        }
        formatter.divisor = divisor;
        return formatter;
    };