Javascript decimal-to-fraction

AsFraction.js

/*
 * Will convert a float to an html fraction, guessing denominators up to 16.  Handles errors from rounding to 2 decimals.
 */
function AsFraction(num) {
    if (num == "" || isNaN(num)) // sanity check
        return num;
    var int = Math.floor(num)
      , decimal = num - int;
    if (decimal < 0.005) // whole number, don't show fraction
        return int;
    if (int == 0) // we know there's a fraction by now, zero ints aren't interesting
        int = "";
    for (var n = 2; n <= 16; n++) {
        // If we take away as many 1/n as possible, is it within tolerance (0 +/- 0.03/n) ?
        if ((decimal + (0.03 / n)) % (1 / n) < 0.06 / n) {
            return int + " <sup>" + Math.round(decimal * n) + "</sup>/<sub>" + n + "</sub>";
        }
    }
    // can't help, return given value to two decimal places
    return Math.round(num * 100) / 100;
}