function flatten_array(myArray){
	myArray = myArray.toString().split(","); // let .toString do all the work for us
	for (var iii = 0; iii < myArray.length; iii++){
		myArray[iii] = +myArray[iii]; // convert all numeric strings back into integers
	}
	return myArray;
}

(function(){ // just a few test cases!
	var test1 = 1;
	var test2 = [1, 2, 3, 4];
	var test3 = [1, [2, 3], 4];
	var test4 = [1, 2, [[3], 4], [[5, 6], [7, 8]], [[[9]]], 10];

	console.log(flatten_array(test1));
	console.log(flatten_array(test2));
	console.log(flatten_array(test3));
	console.log(flatten_array(test4));
})();