If you want to get around the rounding errors with javascript then you need 
to work in cents (or even hundreths of a cent for more accuracy). 

So basically multiply your currency like dollars by 100 to get it into 
cents, do your calculations, then finally, divide by 100 or simply sprintf 
to display in dollars

By using non-fractional numbers, the javascript IEEE 754 floating point 
operations are exact.


Alternatively you could try a decimal or BigNumber implementation in 
javascript, a couple are mentioned in http://stackoverflow.com/a/3439981

Jeff


On Friday, 13 July 2012 05:29:59 UTC-5, Micheil Smith wrote:
>
> Hi Eysenck, 
>
> You may not want to use Node.js (or any javascript vm) for this, due to 
> the inherent issues 
> javascript has dealing with fractional numbers, for instance, take the 
> classic expression: 
>
>         "0.3 - 0.2 != 0.1" 
>
> However, as this is a financial application, you'd probably be storing 
> currency as an integer, 
> not as a float, so you wouldn't have this issue. (ie, store all currency 
> in the lowest fractional, 
> so $19.35 is stored as 1935). 
>
> As for choosing your web framework, you'll definitely want to make sure 
> that the framework 
> is either battle tested or built to a good standard (ie, it'd suck if you 
> had mass-insertion issues 
> in your DB, or if your app crashed and you lost all state of accounts.) 
>
>
> So, the TL;DR; of this is: You could probably use node.js + express for 
> this, but, you'll want to 
> make sure you know node.js first, before jumping down this chasm. You may 
> just be better off 
> using the stack of technologies you already know. 
>
> Kind Regards, 
> Micheil Smith 
> -- 
> BrandedCode.com 
>
>

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