Round number with lots of decimal places in Javascript-CodePudding

I have a number with an extreme amount of decimal places.

1.5583255870000002e 36

I'm struggling to find a good way to round this down to 2 decimal places using JavaScript.

I've tried a few variations using parseFloat() Math.round() and .toFixed().

Here is an example using .toPrecision().

App.currentUSDBalance = Number((App.currentBalance * App.maticPrice).toPrecision(2));

The result is 1.6e 36. I was hoping for something like 1.59.

Thanks,

CodePudding user response：

The following snippet should be the answer to your updated question:

const yourNumber=1.234567890123e36, ndigits=3;

// returns two variations of the solution:
function mySigDig(num,dig){
 return [ (num/(10**Math.floor(Math.log10(num)))).toPrecision(dig),
  num.toPrecision(dig).replace(/e.*/,"")]
}


console.log(mySigDig(23,ndigits));
console.log(mySigDig(2345678,ndigits));
console.log(mySigDig(yourNumber,ndigits));

CodePudding user response：

Apologies for the terrible question.

I ended up solving this by converting to string and dropping the e X.

App.currentUSDBalance = Number((App.currentBalance * App.maticPrice).toPrecision(3)).toString().split('e')[0];

Thanks for the help.