every

Check if every item in a collection satisfies a predicate

every :: (Function predicate, Collection collection) => Boolean|Promise<Boolean> output

description

Returns a Boolean indicating if every item in the input collection satisfies the provided predicate function. It works exactly like Array.prototype.every, except it also accepts Sets, Maps & Objects as inputs, and asynchronous predicates.

Like all functions in conductor, this function is automatically is curried. If the predicate is asynchronous, it will return a Promise, allowing you to use Promise.prototype.then or the await keyword to retrieve the result.

examples

basic example

import { every } from 'conductor'

const numbers = [6, 2, 4]
const isEven = number => number % 2 === 0

every(isEven, numbers) // true

Here, we simply check if every item in our numbers array is an even number. Luckily, that's the case.

using other data structures

import { every } from 'conductor'

const object = { six: 6, two: 2, four: 4}
const set = new Set([6, 2, 4])
const map = new Map([['six', 6], ['two', 2], ['four', 4]])
const isEven = number => number % 2 === 0

every(isEven, object) // true
every(isEven, set) // true
every(isEven, map) // true

every also works on Objects, Sets, and Maps.

using an asynchronous predicate

import { every } from 'conductor'

const numbers = [6, 2, 4]
const isEvenAsync = async number => number % 2 === 0

await every(isEvenAsync, numbers) // true

Here, our predicate is asynchronous (notice the async keyword before the function definition), which makes some return a Promise. We then (no pun intended) simply use the await keyword to retrieve the result.