1.
Introduction
2.
Why This Function is Used
3.
Syntax, Parameter and Return Value
3.1.
Syntax:
3.2.
Parameters:
3.3.
Return Value:
4.
Examples
5.
Rounding to Nearest Integer:
5.1.
JavaScript
5.2.
Rounding with Precision:
5.3.
JavaScript
5.4.
Use in Financial Calculations:
5.5.
JavaScript
5.6.
Application in Data Presentation:
5.7.
JavaScript
6.
6.1.
How does _.round() handle negative numbers?
6.2.
Is _.round() suitable for all rounding needs?
6.3.
Can _.round() be used for large numbers or scientific calculations?
7.
Conclusion
Last Updated: Mar 27, 2024
Easy

# Lodash _.round() Method

Roadmap to SDE career at Amazon
Speaker
Anubhav Sinha
SDE-2 @
25 Jun, 2024 @ 01:30 PM

## Introduction

Rounding numbers to a specified precision is a common requirement in programming, particularly in fields like financial calculations, scientific computing, and data analysis. Lodash's _.round() method simplifies this task by offering an efficient way to round numbers to a certain number of decimal places.

This method is especially useful for ensuring precision and readability in numerical operations.

## Why This Function is Used

The _.round() function is used for rounding numbers to a specified precision. It provides more flexibility than the native JavaScript Math.round() function, which only rounds to the nearest integer. With Lodash's _.round(), you can specify the number of decimal places to which the number should be rounded, making it suitable for various scenarios where precise control over rounding is needed.

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

## Syntax, Parameter and Return Value

### Syntax:

``_.round(number, [precision=0])``

### Parameters:

• number (Number): The number to round.

• [precision=0] (Number): The precision to round to (number of decimal places).

### Return Value:

(Number) - Returns the rounded number.

## Rounding to Nearest Integer:

• JavaScript

### JavaScript

``var _ = require('lodash');console.log(_.round(4.006)); ``

Output:

``4``

Demonstrates rounding a number to the nearest integer.

• JavaScript

### JavaScript

``console.log(_.round(4.006, 2)); ``

Output:

``4.01``

Shows rounding a number to a specified number of decimal places.

• JavaScript

### JavaScript

``var amount = 1234.5678;var roundedAmount = _.round(amount, 2); // Rounding to 2 decimal places for currencyconsole.log(roundedAmount);``

Output:

``1234.57``

An example of using _.round() in financial calculations to round currency amounts.

• JavaScript

### JavaScript

``var data = [1.12345, 2.34567, 3.98765];var roundedData = data.map(num => _.round(num, 3));console.log(roundedData); ``

Output:

``[1.123, 2.346, 3.988]``

Demonstrates rounding an array of numbers for data presentation purposes.

### How does _.round() handle negative numbers?

_.round() rounds negative numbers in the same way as positive numbers, adhering to the specified precision.

### Is _.round() suitable for all rounding needs?

_.round() is ideal for general-purpose rounding to a specified precision. For specific rounding methods (like always rounding up or down), other Lodash methods or native JavaScript functions might be more appropriate.

### Can _.round() be used for large numbers or scientific calculations?

_.round() can be used for large numbers, but for scientific calculations requiring high precision, specialized libraries are recommended to handle floating-point arithmetic accurately.

## Conclusion

Lodash's _.round() method provides a versatile and precise way to round numbers, accommodating various scenarios where control over rounding precision is important. It's a valuable tool for enhancing numerical accuracy and readability in calculations.

You can refer to our guided paths on the Coding Ninjas. You can check our course to learn more about DSADBMSCompetitive ProgrammingPythonJavaJavaScript, etc.

Also, check out some of the Guided Paths on topics such as Data Structure and AlgorithmsCompetitive ProgrammingOperating SystemsComputer Networks, DBMSSystem Design, etc., as well as some Contests, Test Series, and Interview Experiences curated by top Industry Experts.

Live masterclass