JS 浮点计算精密度缺失 _JavaScript

JS 浮点计算精度缺失
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<html>
 <head>
  <title> JS 浮点计算精度问题 </title>
 
 </head>

 <body>
  


<script type="text/javascript">
<!--
    function accDiv(arg1, arg2) {  
      
        var t1 = 0, t2 = 0, t3 = 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(".", ""))  
      
        if (r2 == 0)  
            return 0;  
      
        var result = String(r1 / r2);  
      
        try { t3 = result.toString().split(".")[1].length } catch (e) { }  
      
        var index = t2 - t1 - t3;  
      
        if (index < 0) {  
            result = result.replace(".", "");  
      
            while (result.length <= Math.abs(index)) {  
                result = '0' + result;  
            }  
      
            var start = result.substring(0, result.length + index);  
            var end = result.substring(result.length + index, result.length);  
      
            result = start + '.' + end;  
      
            return Number(result);  
        }  
        else if (index > 0) {  
            result = result.replace(".", "");  
      
            while (result.length <= Math.abs(index)) {  
                result += '0';  
            }  
            return Number(result);  
        }  
        else return Number(result.replace(".", ""));  
      
    }  
      
      
    //给Number类型增加一个div方法，调用起来更加方便。  
      
    Number.prototype.div = function (arg) {  
        /// <summary>  
        ///     除法  
        /// </summary>  
        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) {  
        /// <summary>  
        ///     乘法  
        /// </summary>  
        return accMul(arg, this);  
      
    }  
      
    function accAdd(arg1, arg2) {  
      
        var r1, r2, m, c;  
      
        try { r1 = arg1.toString().split(".")[1].length } catch (e) { r1 = 0 }  
      
        try { r2 = arg2.toString().split(".")[1].length } catch (e) { r2 = 0 }  
      
        c = Math.abs(r1 - r2);  
        m = Math.pow(10, Math.max(r1, r2))  
        if (c > 0) {  
            var cm = Math.pow(10, c);  
            if (r1 > r2) {  
                arg1 = Number(arg1.toString().replace(".", ""));  
                arg2 = Number(arg2.toString().replace(".", "")) * cm;  
            }  
            else {  
                arg1 = Number(arg1.toString().replace(".", "")) * cm;  
                arg2 = Number(arg2.toString().replace(".", ""));  
            }  
        }  
        else {  
            arg1 = Number(arg1.toString().replace(".", ""));  
            arg2 = Number(arg2.toString().replace(".", ""));  
        }  
        return (arg1 + arg2) / m  
      
    }  
      
    Number.prototype.add = function (arg) {  
        /// <summary>  
        ///     加法  
        /// </summary>  
        return accAdd(arg, this);  
    }  

	// 除法，两种写法，都可以，其他一样
	alert(accDiv(2.1,10)); 
	alert(2.1.div(10));
	// 乘法
	alert(accMul(2.1,0.01));
//-->
</script>

 </body>
</html>
JS 浮点计算 精密度缺失

JS 浮点计算精密度缺失
