Serializing and unserializing an array in javascript

You can use JSON.stringify() (MDN docu) and JSON.parse() (MDN docu) for converting a JavaScript object into a string representation to store it inside a database.

var arr = [ 1, 2, 3 ];

var serializedArr = JSON.stringify( arr );
// "[1, 2, 3]"

var unpackArr = JSON.parse( serializedArr );
// identical array to arr

If your backend is written in PHP, there are similar methods to work with JSON strings there: json_encode() (PHP docu) and json_decode() (PHP docu).

Most other languages offer similar functionalities for JSON strings.