js浮点计算--失精度问题解决

//截取n位小数 function cutDec(num,n){ var a=parseFloat(num); var b= Math.pow(10,n); var c = Math.floor(mul(a, b)); return d = div(c, b); } // 浮点数求和 function add(a, b) { var c, d, e; try { c = a.toString().split(".")[1].length; } catch (f) { c = 0; } try { d = b.toString().split(".")[1].length; } catch (f) { d = 0; } return e = Math.pow(10, Math.max(c, d)), (mul(a, e) + mul(b, e)) / e; }

// 浮点数相减 function sub(a, b) { var c, d, e; try { c = a.toString().split(".")[1].length; } catch (f) { c = 0; } try { d = b.toString().split(".")[1].length; } catch (f) { d = 0; } return e = Math.pow(10, Math.max(c, d)), (mul(a, e) - mul(b, e)) / e; }

// 浮点数相乘 function mul(a, b) { var c = 0, d = a.toString(), e = b.toString(); try { c += d.split(".")[1].length; } catch (f) {} try { c += e.split(".")[1].length; } catch (f) {} return Number(d.replace(".", "")) * Number(e.replace(".", "")) / Math.pow(10, c); }

// 浮点数相除 function div(a, b) { var c, d, e = 0, f = 0; try { e = a.toString().split(".")[1].length; } catch (g) {} try { f = b.toString().split(".")[1].length; } catch (g) {} return c = Number(a.toString().replace(".", "")), d = Number(b.toString().replace(".", "")), mul(c / d, Math.pow(10, f - e)); }

//浮点数除整数 function div(a, b) { var c, d, e = 0, f = 0; try { e = a.toString().split(".")[1].length; } catch (g) {} try { f = b.toString().split(".")[1].length; } catch (g) {} return c = Number(a.toString().replace(".", "")), d = Number(b.toString().replace(".", "")), mul(c / d, Math.pow(10, f - e)); }