How to Convert a Floating-Point Number to a Whole Number in JavaScript?

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Converting a floating-point number to a whole number is something that we’ve to do sometimes in JavaScript apps.

In this article, we’ll look at how to convert a JavaScript floating-point number to a whole number.

The Math.floor method lets us round a number down to the nearest integer.

For instance, we can use it by writing:

const intvalue = Math.floor(123.45);  
console.log(intvalue)

Then we get 123 as the value of intValue .

The Math.ceil method lets us round a number up to the nearest integer.

For instance, we can write:

const intvalue = Math.ceil(123.45);  
console.log(intvalue)

Then intValue is 124.

The Math.round method lets us round a number down to the nearest integer if the first decimal digit is 4 or lower.

Otherwise, it rounds the number up to the nearest integer.

For instance, if we have:

const intvalue = Math.round(123.45);  
console.log(intvalue)

Then intValue is 123.

The Math.trunc method lets us return the integer part of a number by removing the fractional digits.

For example, we can write:

const intvalue = Math.trunc(123.45);  
console.log(intvalue)

Then intValue is 123.

The parseInt function lets us convert a floating-point number to an integer.

It works like Math.trunc in that it removes the fractional digits from the returned number.

For example, we can write:

const intvalue = parseInt(123.45);  
console.log(intvalue)

And intValue is 123.

To make sure that we return a decimal number, we pass 10 into the 2nd argument:

const intvalue = parseInt(123.45, 10);  
console.log(intvalue)

JavaScript provides a few functions and methods to lets us convert floating-point numbers to integers.

By John Au-Yeung