javascript精度计算

function accDiv(arg1, arg2) {
	var t1 = 0, t2 = 0, r1, r2;
	try {
		t1 = arg1.toString().split(".")[1].length
	} catch (e) {
	}
	try {
		t2 = arg2.toString().split(".")[1].length
	} catch (e) {
	}
	with (Math) {
		r1 = Number(arg1.toString().replace(".", ""))
		r2 = Number(arg2.toString().replace(".", ""))
		return (r1 / r2) * pow(10, t2 - t1);
	}
}
Number.prototype.div = function(arg) {
	return accDiv(this, arg);
}

function accMul(arg1, arg2) {
	var m = 0, s1 = arg1.toString(), s2 = arg2.toString();
	try {
		m += s1.split(".")[1].length
	} catch (e) {
	}
	try {
		m += s2.split(".")[1].length
	} catch (e) {
	}
	return Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m)
}

Number.prototype.mul = function(arg) {
	return accMul(arg, this);
}

function accAdd(arg1, arg2) {
	var r1, r2, m;
	try {
		r1 = arg1.toString().split(".")[1].length
	} catch (e) {
		r1 = 0
	}
	try {
		r2 = arg2.toString().split(".")[1].length
	} catch (e) {
		r2 = 0
	}
	m = Math.pow(10, Math.max(r1, r2))
	return (arg1 * m + arg2 * m) / m
}
// 给Number类型增加一个add方法，调用起来更加方便。
Number.prototype.add = function(arg) {
	return accAdd(arg, this);
}

function Subtr(arg1, arg2) {
	var r1, r2, m, n;
	try {
		r1 = arg1.toString().split(".")[1].length
	} catch (e) {
		r1 = 0
	}
	try {
		r2 = arg2.toString().split(".")[1].length
	} catch (e) {
		r2 = 0
	}
	m = Math.pow(10, Math.max(r1, r2));
	// last modify by deeka
	// 动态控制精度长度
	n = (r1 >= r2) ? r1 : r2;
	return ((arg1 * m - arg2 * m) / m).toFixed(n);
}