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How to Format a Floating Point Number in JavaScript?

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Oftentimes, we have to format a floating-point number into the format we want in JavaScript.

In this article, we’ll look at how to format a floating-point number into the format we want with JavaScript.

Math.round

We can use Math.round to round a number into the number of decimal places we want by multiplying the original number 10 to the power of the number of decimal places we want to round to.

Then we pass that number into Math.round , and we divide the rounded number by the same number we multiplied the original number with.

For instance, we can write:

const original = 123.456
const result = Math.round(original * 100) / 100;
console.log(result)

We multiply original by 100, which is 10 to the power of 2.

So we round to 2 decimal places.

And we divide by 100.

Then result is 123.46.

This also works if we also round to other numbers of decimal places.

For instance, we can write:

const original = 123.45678
const result = Math.round(original * 1000) / 1000;
console.log(result)

And result is 123.457.

Number.prototype.toFixed

We can call the toFixed method to return a string with the number rounded to the given number of decimal places.

For instance, we can write:

const original = 123.45678
const result = original.toFixed(3)
console.log(result)

Then result is ‘123.457’ .

3 is the number of decimal places to round to.

result is a string instead of number in the previous example.

This is the easier way to format a number to the number of decimal places we want.

Conclusion

We can format a floating-point number into the number of decimal places we want with Math.round or the number’s toFixed method.

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