source : https://www.geeksforgeeks.org/how-to-get-all-the-methods-of-an-object-using-javascript/

var result = [];
for (var id in attribute) {
    try {
        if (typeof (attribute[id]) == "function") {
            result.push(id + ": " + attribute[id].toString());
        }
    } catch (err) {
        result.push(id + ": Not accessible");
    }
}