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]: 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:
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