javascript 浮点数精确计算

1、加法

function floatAdd(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;
}

2、减法

function floatSub(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));
	// 动态控制精度长度 
	n = (r1 >= r2) ? r1 : r2;
	return ((arg1 * m - arg2 * m) / m).toFixed(n);
}

3、乘法

function floatMul(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);
}

4、除法

function floatDiv(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) { }

	r1 = Number(arg1.toString().replace(".", ""));

	r2 = Number(arg2.toString().replace(".", ""));
	return (r1 / r2) * Math.pow(10, t2 - t1);
}