reduce js object code example

Example 1: how to flatten array with reduce in javascript

let flattened = [[0, 1], [2, 3], [4, 5]].reduce(
  function(accumulator, currentValue) {
    return accumulator.concat(currentValue)
  },
  []
)
// flattened is [0, 1, 2, 3, 4, 5]

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 mdn

arr.reduce(callback( accumulator, currentValue[, index[, array]] )[, initialValue])

Example 4: javascript, reduce

const myReduce = myArray.reduce((acc, item) => {
	acc += item
})

Example 5: object.entries reduce

.as-console-wrapper {  max-height: 100% !important;  top: 0;}

Example 6: reduce mdn

array.reduce(callback( accumulator, valueNow[, index[, array]] )[, initialValue]))