Example 1: javascript reduce array of objects
var objs = [
{name: "Peter", age: 35},
{name: "John", age: 27},
{name: "Jake", age: 28}
];
objs.reduce(function(accumulator, currentValue) {
return accumulator + currentValue.age;
}, 0);
Example 2: creating array of objects usinng reduce js
const 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]};
}, {});
Example 3: reduce object to array javascript
var arr = [{x:1},{x:2},{x:4}];
arr.reduce(function (a, b) {
return {x: a.x + b.x};
})
arr.reduce((a, b) => ({x: a.x + b.x}));
Example 4: js reduce
Sum array elements:
let myArr = [1,2,3,-1,-34,0]
return myArr.reduce((a,b) => a + b,0)
Example 5: .reduce mdn
arr.reduce(callback( accumulator, currentValue[, index[, array]] )[, initialValue])
Example 6: reduce javascript acc became numeber insted array
const secondArray = [1, 2, 3].reduce((acc, item) => {
acc.push(1);
return acc;
}, []);
console.log(secondArray);