Split an array into chunks

chunk.js

let partition = ( a, n ) => a.length ? [ a.splice( 0, n ), ...partition( a, n ) ] : [];

partition( [ 1, 2, 3, 4, 5, 6, 7, 8 ], 2 );

// [
//     [ 1, 2 ],
//     [ 3, 4 ],
//     [ 5, 6 ],
//     [ 7, 8 ]
// ]