当我们在前端使用js来执行运算时，会有丢失精度的问题。

例如：

console.log("使用js原生态方法");
console.log(" 1.01 + 1.02 ="+(1.01 + 1.02));
console.log(" 1.01 - 1.02 ="+(1.01 - 1.02));
console.log(" 0.000001 / 0.0001 ="+(0.000001 / 0.0001));
console.log(" 0.012345 * 0.000001 ="+(0.012345 * 0.000001));
    
-----------------------------------
输出结果：
使用js原生态方法
1.01 + 1.02 =2.0300000000000002
1.01 - 1.02 =-0.010000000000000009
0.000001 / 0.0001 =0.009999999999999998
0.012345 * 0.000001 =1.2344999999999999e-8

解决方法：

<script type="text/javascript">
    // 两个浮点数求和
    function accAdd(num1,num2){
       var r1,r2,m;
       try{
           r1 = num1.toString().split('.')[1].length;
       }catch(e){
           r1 = 0;
       }
       try{
           r2=num2.toString().split(".")[1].length;
       }catch(e){
           r2=0;
       }
       m=Math.pow(10,Math.max(r1,r2));
       // return (num1*m+num2*m)/m;
       return Math.round(num1*m+num2*m)/m;
    }
    
    // 两个浮点数相减
    function accSub(num1,num2){
       var r1,r2,m;
       try{
           r1 = num1.toString().split('.')[1].length;
       }catch(e){
           r1 = 0;
       }
       try{
           r2=num2.toString().split(".")[1].length;
       }catch(e){
           r2=0;
       }
       m=Math.pow(10,Math.max(r1,r2));
       n=(r1>=r2)?r1:r2;
       return (Math.round(num1*m-num2*m)/m).toFixed(n);
    }
 
    // 两个浮点数相除
    function accDiv(num1,num2){
       var t1,t2,r1,r2;
       try{
           t1 = num1.toString().split('.')[1].length;
       }catch(e){
           t1 = 0;
       }
       try{
           t2=num2.toString().split(".")[1].length;
       }catch(e){
           t2=0;
       }
       r1=Number(num1.toString().replace(".",""));
       r2=Number(num2.toString().replace(".",""));
       return (r1/r2)*Math.pow(10,t2-t1);
    }
    
       // 两个浮点数相乘
    function accMul(num1,num2){
       var m=0,s1=num1.toString(),s2=num2.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);
    }
    
  </script>
  
  <script>
console.log("使用js原生态方法");
    console.log(" 1.01 + 1.02 ="+(1.01 + 1.02));
    console.log(" 1.01 - 1.02 ="+(1.01 - 1.02));
    console.log(" 0.000001 / 0.0001 ="+(0.000001 / 0.0001));
    console.log(" 0.012345 * 0.000001 ="+(0.012345 * 0.000001));
    console.log("-----------------");
    console.log("使用自定义方法");
    console.log(" 1.01 + 1.02 ="+accAdd(1.01,1.02));
    console.log(" 1.01 - 1.02 ="+accSub(1.01,1.02));
    console.log(" 0.000001 / 0.0001 ="+accDiv(0.000001,0.0001));
    console.log(" 0.012345 * 0.000001 ="+accMul(0.012345,0.000001)); 
  </script> 



------------------
输出结果

使用js原生态方法
1.01 + 1.02 =2.0300000000000002
1.01 - 1.02 =-0.010000000000000009
0.000001 / 0.0001 =0.009999999999999998
0.012345 * 0.000001 =1.2344999999999999e-8
-----------------
使用自定义方法：
1.01 + 1.02 =2.03
1.01 - 1.02 =-0.01
0.000001 / 0.0001 =0.01
0.012345 * 0.000001 =1.2345e-8

链接: https://www.fly63.com/article/detial/9153