# Array is contained in other array

JavaScript, Array · Oct 22, 2020

Checks if the elements of the first array are contained in the second one regardless of order.

- Use a
`for...of`

loop over a`Set`

created from the first array. - Use
`Array.prototype.some()`

to check if all distinct values are contained in the second array. - Use
`Array.prototype.filter()`

to compare the number of occurrences of each distinct value in both arrays. - Return
`false`

if the count of any element is greater in the first array than the second one,`true`

otherwise.

const isContainedIn = (a, b) => { for (const v of new Set(a)) { if ( !b.some(e => e === v) || a.filter(e => e === v).length > b.filter(e => e === v).length ) return false; } return true; }; isContainedIn([1, 4], [2, 4, 1]); // true