Lodash _.sumBy() Method

Lodash _.sumBy() method is used to compute the sum from the original array by iterating over each element in the array by using the Iteratee function. It is almost the same as the _.sum() method.

Syntax:

_.sumBy(array, [iteratee = _.identity]);

Parameters:

• array: This parameter holds the array to iterate over.
• [iteratee = _.identity]:  This parameter holds the iteratee invoked per element.

Return Value:

This method returns the sum.

Example 1: In this example, we are returning the sum of an array having objects as values by the use of the _.sumBy() method.

// Requiring the lodash library  
const _ = require("lodash");

// Original array 
let arr = [{ 'n': 4 }, { 'n': 2 }, { 'n': 6 }];

// Use of _.sumBy()  
// method 
let gfg = _.sumBy(arr, function (o) { return o.n; });

// Printing the output  
console.log(gfg);

Output:

12

Example 2: In this example, we are returning the sum of an array having objects as values by the use of the _.sumBy() method.

// Requiring the lodash library  
const _ = require("lodash");

// Original array 
let arr = [{ 'n': 10 }, { 'n': 5 }, { 'n': 3 }, { 'n': 12 }];

// Use of _.sumBy()  
// method 
let gfg = _.sumBy(arr, 'n');

// Printing the output  
console.log(gfg);

Output:

30