Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, strings, objects, numbers, etc.
The _.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 _.sum() method.
Syntax:
_.sumBy(array, [iteratee = _.identity])
Parameters: This method accepts two parameters as mentioned above and described below:
- array: This parameter holds the array to iterate over.
- [iteratee = _.identity]: Â This parameter holds the iteratee invoked per element.
Return Value: This method returns the sum.
Example 1: Here, const _ = require(‘lodash’) is used to import the lodash library into the file.
Javascript
// Requiring the lodash library  const _ = require("lodash");     // Original array var 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: Â
Javascript
// Requiring the lodash library  const _ = require("lodash");     // Original array var 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
