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Table of contents
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.
Frequently Asked Questions
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
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Lodash _.round() Method

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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.

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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.

Examples 

Rounding to Nearest Integer:

  • JavaScript

JavaScript

var _ = require('lodash');

console.log(_.round(4.006));

Output: 

4


Demonstrates rounding a number to the nearest integer.

Rounding with Precision:

  • JavaScript

JavaScript

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

Output: 

4.01


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

Use in Financial Calculations:

  • JavaScript

JavaScript

var amount = 1234.5678;

var roundedAmount = _.round(amount, 2); // Rounding to 2 decimal places for currency

console.log(roundedAmount);

 Output: 

1234.57


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

Application in Data Presentation:

  • 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.

Frequently Asked Questions

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.

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