Function roundNumber

test/angular/1.4/angular.js:19137–19173

* Round the parsed number to the specified number of decimal places * This function changed the parsedNumber in-place

(parsedNumber, fractionSize, minFrac, maxFrac)

 * This function changed the parsedNumber in-place
 */
function roundNumber(parsedNumber, fractionSize, minFrac, maxFrac) {
    var digits = parsedNumber.d;
    var fractionLen = digits.length - parsedNumber.i;

    // determine fractionSize if it is not specified; `+fractionSize` converts it to a number
    fractionSize = (isUndefined(fractionSize)) ? Math.min(Math.max(minFrac, fractionLen), maxFrac) : +fractionSize;

    // The index of the digit to where rounding is to occur
    var roundAt = fractionSize + parsedNumber.i;
    var digit = digits[roundAt];

    if (roundAt > 0) {
      digits.splice(roundAt);
    } else {
      // We rounded to zero so reset the parsedNumber
      parsedNumber.i = 1;
      digits.length = roundAt = fractionSize + 1;
      for (var i=0; i < roundAt; i++) digits[i] = 0;
    }

    if (digit >= 5) digits[roundAt - 1]++;

    // Pad out with zeros to get the required fraction length
    for (; fractionLen < fractionSize; fractionLen++) digits.push(0);


    // Do any carrying, e.g. a digit was rounded up to 10
    var carry = digits.reduceRight(function(carry, d, i, digits) {
      d = d + carry;
      digits[i] = d % 10;
      return Math.floor(d / 10);
    }, 0);
    if (carry) {
      digits.unshift(carry);
      parsedNumber.i++;
    }
}

/**
 * Format a number into a string