Lodash - sumBy method

Syntax

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

This method is like _.sum except that it accepts iteratee which is invoked for each element in array to generate the value to be summed. The iteratee is invoked with one argument: (value).

Arguments

• array (Array) − The array to iterate over.

• [iteratee=_.identity] (Function) − The iteratee invoked per element.

Output

• (number) − Returns the sum.

Example

var _ = require('lodash');
var values = [{ 'n': 1 }, { 'n': 2 }, { 'n': 3 }];
var result = _.sumBy(values, function(item) { return item.n; });

console.log(result);
 
result = _.sumBy(values, 'n');
console.log(result);

Save the above program in tester.js. Run the following command to execute this program.

Command

\>node tester.js

Output

6
6