massCode
Array
Compact
This snippet removes false values from an array.
js
const compact = arr => arr.filter(Boolean)
Example
js
compact([0, 1, false, 2, '', 3, 'a', 'e' * 23, NaN, 's', 34])
// [ 1, 2, 3, 'a', 's', 34 ]
Intersection
This snippet can be used to get an array with elements that are included in two other arrays.
js
const intersection = (a, b) => {
const s = new Set(b)
return a.filter(i => s.has(i))
}
Example
js
intersection([1, 2, 3], [4, 3, 2]) // [2, 3]
Intersection by
This snippet can be used to return a list of elements that exist in both arrays, after a particular function has been executed to each element of both arrays.
js
const intersectionBy = (a, b, fn) => {
const s = new Set(b.map(fn))
return a.filter(x => s.has(fn(x)))
}
Example
js
intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor) // [2.1]
Intersection with
This snippet can be used to return a list of elements that exist in both arrays by using a comparator function.
js
const intersectionWith = (a, b, comp) =>
a.filter(x => b.findIndex(y => comp(x, y)) !== -1)
Example
js
const arr1 = [1, 1.2, 1.5, 3, 0]
const arr2 = [1.9, 3, 0, 3.9]
const fn = (a, b) => Math.round(a) === Math.round(b)
intersectionWith(arr1, arr2, (a, b) => fn(a, b)) // [1.5, 3, 0]
Is null
This snippet can be used to check whether a value is null.
js
const isNull = val => val === null
Example
js
isNull(null) // true
Last
This snippet returns the last element of an array.
js
const last = arr => arr[arr.length - 1]
Example
js
last([1, 2, 3, 4]) // 4
Random
This snippet can be used to get a random number from an array.
js
const random = arr => arr[Math.floor(Math.random() * arr.length)]
Example
js
random([3, 1, 4, 11]) // 4
With Length
This snippet get an array with specified length.
js
const withLength = n => new Array(n).fill('')
Example
js
withLength(5) // ['', '', '', '', '']
Uniq
This snippet get uniq values in an array.
js
const uniq = arr => [...new Set(arr)]
Example
js
uniq(1, 1, 2, 3, 4, 4) // [1, 2, 3, 4]