var objs = [
{name: "Peter", age: 35},
{name: "John", age: 27},
{name: "Jake", age: 28}
];
objs.reduce(function(accumulator, currentValue) {
return accumulator + currentValue.age;
}, 0); // 35 + 27 + 28 = 90const posts = [
{id: 1, category: "frontend", title: "All About That Sass"},
{id: 2, category: "backend", title: "Beam me up, Scotty: Apache Beam tips"},
{id: 3, category: "frontend", title: "Sanitizing HTML: Going antibactirial on XSS attacks"}
];
const categoryPosts = posts.reduce((acc, post) => {
let {id, category} = post;
return {...acc, [category]: [...(acc[category] || []), id]};
}, {});
var arr = [{x:1},{x:2},{x:4}];
arr.reduce(function (a, b) {
return {x: a.x + b.x}; // returns object with property x
})
// ES6
arr.reduce((a, b) => ({x: a.x + b.x}));
// -> {x: 7}arr.reduce(callback( accumulator, currentValue[, index[, array]] )[, initialValue])