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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 
4.1.
Finding Object with Maximum Property Value:
4.2.
JavaScript
4.3.
Using Property Name Shorthand:
4.4.
Max Value in Array of Arrays:
4.5.
JavaScript
4.6.
Custom Iteratee Function:
4.7.
JavaScript
5.
Frequently Asked Questions
5.1.
How does _.maxBy() differ from _.max()?
5.2.
Can _.maxBy() handle non-numeric comparisons?
5.3.
What happens if multiple elements meet the maximum criterion?
6.
Conclusion
Last Updated: Mar 27, 2024
Easy

Lodash _.maxBy() Method

Author Gaurav Gandhi
0 upvote

Introduction

In data processing and analysis, finding the maximum value in a collection based on a specific criterion is a common requirement. Lodash's _.maxBy() method addresses this need by allowing you to find the maximum element in an array based on the value returned by an iteratee function. 

Lodash _.maxBy() Method

This is particularly useful when dealing with arrays of objects, where you need to determine the maximum based on a property of the objects.

Why This Function is Used

The _.maxBy() function is used to find the element with the maximum value in an array based on a specific criterion defined by an iteratee. This method is essential when working with collections of complex objects where the maximum needs to be calculated based on a property or computed value, not just on the objects themselves. It simplifies the process of identifying the 'largest' or 'highest' item in a collection according to a defined parameter.

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Syntax, Parameter and Return Value

Syntax: 

_.maxBy(array, [iteratee=_.identity])

Parameters:

  • array (Array): The array to iterate over.
     
  • [iteratee=_.identity] (Function): The iteratee invoked per element.

Return Value: 

Returns the element with the maximum value.

Examples 

Finding Object with Maximum Property Value:

  • JavaScript

JavaScript

var _ = require('lodash');

var users = [

 { 'user': 'fred', 'age': 48 },

 { 'user': 'barney', 'age': 36 },

 { 'user': 'fred', 'age': 40 }

];

var oldestUser = _.maxBy(users, (o) => o.age);

console.log(oldestUser);

Output:

{ 'user': 'fred', 'age': 48 }


Demonstrates finding the user with the highest age in an array of user objects.

Using Property Name Shorthand:

var mostExpensiveProduct = _.maxBy(products, 'price');
console.log(mostExpensiveProduct);


An example of using property name shorthand to find the most expensive product.

Max Value in Array of Arrays:

  • JavaScript

JavaScript

var points = [[1, 2], [3, 4], [2, 8]];

var highestPoint = _.maxBy(points, (p) => p[1]);

console.log(highestPoint);

Output: 

[2, 8]


Shows finding the point with the highest y-value in an array of coordinates.

Custom Iteratee Function:

  • JavaScript

JavaScript

var data = [

 { name: 'Item1', dimensions: { width: 10, height: 5 }},

 { name: 'Item2', dimensions: { width: 4, height: 20 }}

];

var largestAreaItem = _.maxBy(data, item => item.dimensions.width * item.dimensions.height);

console.log(largestAreaItem.name);

Output: 

'Item2'


Uses a custom function to determine the item with the largest area.

Frequently Asked Questions

How does _.maxBy() differ from _.max()?

_.max() finds the maximum numeric value in a simple array, while _.maxBy() is used for finding the maximum value in an array based on a specific criterion or property.

Can _.maxBy() handle non-numeric comparisons?

Yes, _.maxBy() can be used for non-numeric comparisons, as long as the iteratee function returns a value that can be logically ordered (like strings or dates).

What happens if multiple elements meet the maximum criterion?

If multiple elements are considered 'maximum', _.maxBy() returns the first one encountered in the collection.

Conclusion

Lodash's _.maxBy() method is a versatile tool for identifying the maximum element in a collection based on a defined criterion. It is particularly valuable when working with arrays of objects and needing to determine the maximum based on a property or a result of a function.

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