src/lolex-src.js
function nanoRemainder(msFloat) {
        var modulo = 1e6;
        var remainder = (msFloat * 1e6) % modulo;
        var positiveRemainder = remainder < 0 ? remainder + modulo : remainder;

        return Math.floor(positiveRemainder);
    }
function nanoRemainder(msFloat) {
        var modulo = 1e6;
        var remainder = (msFloat * 1e6) % modulo;
        var positiveRemainder = remainder < 0 ? remainder + modulo : remainder;

        return Math.floor(positiveRemainder);
    }
Get the decimal part of the millisecond value as nanoseconds

@param {Number} msFloat the number of milliseconds
@returns {Number} an integer number of nanoseconds in the range [0,1e6)

Example: nanoRemainer(123.456789) -> 456789