Display in baseScalar units without changing to SI units about js-quantities HOT 2 OPEN

Qty('10 kW').toPrefix() // outputs quantity with '10000 W'
Qty('10 kW').toPrefix('M') // outputs quantity with '0.01 MW'

// Get prefix from unit, eg. 'kW' --> 'k'
function get_prefix(qty) {
	var prefix;
	if (UNITS[qty.numerator[0]][2] == "prefix") {
		prefix = UNITS[qty.numerator[0]][0][0];
	}
	else {
		prefix = "";
	}
	return prefix;
}

// Get unit base, eg. 'kW' --> 'W'
function get_unit_base(qty) {
	var unit_base, prefix;
	prefix = get_prefix(qty);
	if (prefix.length === 1) {
		unit_base = qty.units().substr(1);
	}
	else {
		unit_base = qty.units();
	}
	return unit_base;
}

// Convert unit to defined prefix,
// eg. no prefix: '0.1 kW' --> '100 W'  or  prefix 'm': '0.35 W' --> '350 mW'
function convert_prefix(qty, prefix) {
	var prefix, unit_base, target, qty, q;
	if (prefix == undefined || prefix == null || prefix == 1) {
		prefix = "";
	}
	unit_base = get_unit_base(qty);
	target = Qty(prefix+unit_base);
	q = divSafe(qty.baseScalar, target.baseScalar);
	target = Qty({"scalar": q, "numerator": target.numerator, "denominator": target.denominator});
	return target;
}

// ... //

assign(Qty.prototype, {
// ... //
  toPrefix: function(prefix) {
	  return convert_prefix(this,prefix);
  },
// ... //
}