做个记录，以备不时之需
//加法 ??????Number.prototype.add = function(arg){ ??????????var r1,r2,m; ??????????try{r1=this.toString().split(".")[1].length}catch(e){r1=0} ??????????try{r2=arg.toString().split(".")[1].length}catch(e){r2=0} ??????????m=Math.pow(10,Math.max(r1,r2)) ??????????return (this*m+arg*m)/m ??????} ?//减法 ??Number.prototype.sub = function (arg){ ??????return this.add(-arg); ??} ??//乘法 ??Number.prototype.mul = function (arg) ??{ ??????var m=0,s1=this.toString(),s2=arg.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) ??} ??//除法 ??Number.prototype.div = function (arg){ ??????var t1=0,t2=0,r1,r2; ??????try{t1=this.toString().split(".")[1].length}catch(e){} ??????try{t2=arg.toString().split(".")[1].length}catch(e){} ??????with(Math){ ??????????r1=Number(this.toString().replace(".","")) ??????????r2=Number(arg.toString().replace(".","")) ??????????return (r1/r2)*pow(10,t2-t1); ??????} ??}js浮点数加减乘除精度不准确
原文地址：https://www.cnblogs.com/fancyLee/p/9601037.html