iamvanja · February 21, 2017 03:23
diff --git a/index.js b/index.js
 var flatten = function(arr) {
    return arr.reduce(function (flat, toFlatten) {
        return flat.concat(Array.isArray(toFlatten) ? flatten(toFlatten) : toFlatten);
    }, []);
 }

 flatten([[1,2,[3]],4]); // [1,2,3,4]
	var flatten = function(arr) {
	return arr.reduce(function (flat, toFlatten) {
	return flat.concat(Array.isArray(toFlatten) ? flatten(toFlatten) : toFlatten);
	}, []);
	}

	flatten([[1,2,[3]],4]); // [1,2,3,4]