Learn How to Remove the Decimal Part of a Number in JavaScript

In the world of programming, precision matters. There are instances when you need to manipulate numbers and perform calculations without dealing with the decimal part. In JavaScript, a versatile and widely-used programming language for the web, you can achieve this by removing the decimal part of a number. In this article, we’ll explore various methods to accomplish this task and provide you with detailed code snippet examples. Whether you’re a beginner or an experienced developer, understanding how to remove the decimal part of a number in JavaScript can greatly enhance your programming skills.


When working with numbers in JavaScript, there might be situations where you want to eliminate the decimal portion and work only with the whole number. This could be for formatting purposes, mathematical operations, or any other specific requirement. Let’s dive into some methods that can help us achieve this goal.

Using Math. floor()

One of the simplest ways to remove the decimal part of a number is by using the Math.floor() function. This function rounds down a number to the nearest integer, effectively removing the decimal portion. Here’s an example:

let originalNumber = 7.89;
let wholeNumber = Math.floor(originalNumber);
console.log(wholeNumber); // Output: 7

Using parseInt()

The parseInt() function can also be used to achieve this task. Although commonly used for converting strings to integers, it can also remove the decimal part of a number. However, note that this method works only if the number is represented as a string:

let originalNumber = "5.67";
let wholeNumber = parseInt(originalNumber);
console.log(wholeNumber); // Output: 5

Using parseFloat()

Similar to parseInt(), the parseFloat() function can be employed to remove the decimal part of a number. This method is more suitable when dealing with floating-point numbers:

let originalNumber = 9.45;
let wholeNumber = parseFloat(originalNumber);
console.log(wholeNumber); // Output: 9

Using Math.trunc()

The Math.trunc() function truncates the decimal part of a number, essentially removing it. Unlike Math.floor(), this method doesn’t round the number but simply removes everything after the decimal point:

let originalNumber = 3.75;
let wholeNumber = Math.trunc(originalNumber);
console.log(wholeNumber); // Output: 3

Handling Edge Cases

While the above methods work well in most cases, it’s important to consider edge cases, such as non-numeric inputs or very large numbers. To handle such scenarios, you can add validations before applying the methods to ensure accurate results.

Best Practices

When removing the decimal part of a number in JavaScript, keep the following best practices in mind:

  • Choose the method that best suits your use case: Depending on the situation, one method might be more appropriate than the others.
  • Validate inputs: Always validate the input to ensure it’s a valid number before applying any method.
  • Comment your code: Add comments to explain the purpose of the code and any specific details about the chosen method.


If you encounter unexpected results when removing the decimal part of a number, consider the following troubleshooting steps:

  • Check for input validity: Ensure that the input is indeed a valid number and doesn’t contain any non-numeric characters.
  • Review the method documentation: Consult the documentation for the chosen method to understand its behavior and potential limitations.
  • Test with different inputs: Try your code with various inputs to identify any patterns that might lead to unexpected behavior.


In this article, we explored different methods to remove the decimal part of a number in JavaScript. Whether you choose to use Math.floor(), parseInt(), parseFloat(), or Math.trunc(), each method has its own characteristics and use cases. By understanding these methods and their nuances, you’ll be better equipped to manipulate numbers in your JavaScript projects.


Can I use these methods with negative numbers?

Yes, these methods work with both positive and negative numbers.

Which method should I choose for better performance?

In terms of performance, Math.trunc() is generally faster, but the difference is negligible for most use cases

Will these methods work with non-numeric inputs?

No, these methods are designed to work with numeric inputs. Ensure that you validate the input before applying any of these methods.

Is there a method to remove decimals and round to the nearest whole number?

Yes, if rounding is your goal, consider using the Math.round() function instead.

Where can I learn more about JavaScript number manipulation?

You can explore the official Mozilla Developer Network (MDN) documentation for JavaScript to gain a deeper understanding of number manipulation techniques.

Leave a Comment