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Underscore Extension Methods Sum

Maxime LUCE edited this page Apr 10, 2015 · 1 revision

Allow to sum collection values by using given iterator.

Usage

Introduction
var myArray = [
    { productId: 1, title: 'My Product 1', price: 10, quantity: 1 },
    { productId: 2, title: 'My Product 2', price: 15.5, quantity: 3 },
    { productId: 3, title: 'My Product 3', price: 7.25, quantity: 1 }
];
Simple usage
var numberOfArticles = _.sum(myArray, function(obj) { return obj.quantity; });
// numberOfArticles === 5
Complex usage
var total = _.sum(myArray, function(obj) { return obj.price * obj.quantity; });
// total === 63.75