# A brief analysis of floating point arithmetic in js

• 2020-03-30 01:12:43
• OfStack

How do we compute floating point in js?

For example, var a=0.69;

I want to get 6.9 let me just write it this way var c is equal to a times 10;

Search to the Internet, a netizen said that this is a JS floating point arithmetic Bug, found a solution:

Method 1: there are js custom functions

``````
<script>
//Note: javascript addition results will have errors, in the two floating point Numbers will be more obvious when adding. This function returns a more accurate addition result.
//Return value: the exact result of arg1 plus arg2
var r1,r2,m;
try{r1=arg1.toString().split(".").length}catch(e){r1=0}
try{r2=arg2.toString().split(".").length}catch(e){r2=0}
m=Math.pow(10,Math.max(r1,r2))
return (arg1*m+arg2*m)/m
}
//Add an add method to the Number type to make it easier to call.
}
//Note: javascript addition results will have errors, in the two floating point Numbers will be more obvious when adding. This function returns a more accurate addition result.
//Return value: the exact result of arg1 plus arg2
function accSub(arg1,arg2){
var r1,r2,m,n;
try{r1=arg1.toString().split(".").length}catch(e){r1=0}
try{r2=arg2.toString().split(".").length}catch(e){r2=0}
m=Math.pow(10,Math.max(r1,r2));
//last modify by deeka
//Dynamic control precision length
n=(r1>=r2)?r1:r2;
return ((arg1*m-arg2*m)/m).toFixed(n);
}
//Division function, used to get accurate division results
//Note: javascript division results will have errors, in two floating point division will be more obvious. This function returns a more precise division result.
//Call: accDiv (arg1, arg2)
//Return value: the exact result of arg1 divided by arg2
function accDiv(arg1,arg2){
var t1=0,t2=0,r1,r2;
try{t1=arg1.toString().split(".").length}catch(e){}
try{t2=arg2.toString().split(".").length}catch(e){}
with(Math){
r1=Number(arg1.toString().replace(".",""))
r2=Number(arg2.toString().replace(".",""))
return (r1/r2)*pow(10,t2-t1);
}
}
//Add a div method to the Number type to make it easier to call.
Number.prototype.div = function (arg){
return accDiv(this, arg);
}
//The multiplication function, which is used to get exact multiplication results
//Note: javascript multiplication results will have errors, in the two floating point number multiplication will be more obvious. This function returns a more precise multiplication result.
//Call: accMul (arg1, arg2)
//Return value: the exact result of arg1 times arg2
function accMul(arg1,arg2)
{
var m=0,s1=arg1.toString(),s2=arg2.toString();
try{m+=s1.split(".").length}catch(e){}
try{m+=s2.split(".").length}catch(e){}
return Number(s1.replace(".",""))*Number(s2.replace(".",""))/Math.pow(10,m)
}
//Add a mul method to the Number type to make it easier to call.
Number.prototype.mul = function (arg){
return accMul(arg, this);
}
var a=0.69;
var b=10;