nford · October 25, 2016 19:25
diff --git a/flatten.js b/flatten.js
 var arr = [[1,2,[3]],4,[5,6,[7],8,[9,[10,11,12,[13]]]]];

 const flatten = (arr) => arr.reduce(
    (a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []
 );

 flatten(arr);
	var arr = [[1,2,[3]],4,[5,6,[7],8,[9,[10,11,12,[13]]]]];

	const flatten = (arr) => arr.reduce(
	(a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []
	);

	flatten(arr);