create nested json from html

$('#saveNewTasklist').on("click", function () {
    const nestedQuery = '.nested-sortable';
    const identifier = 'taskId';
    const root = document.getElementById('tasks');
    function serialize(tasks) {
        var serialized = [];
        var children = [].slice.call(tasks.children); // children == document property
        /**
         * [].slice.call() == Array.prototype.slice.call()
         * 
         * call slice() as if it was a function of NodeList using call(). What slice() does in this case is create an empty array, then iterate through the object it's running on (originally an array, now a NodeList) and keep appending the elements of that object to the empty array it created, which is eventually returned.
         */
        for (var i in children) {
            var nested = children[i].querySelector(nestedQuery);
            serialized.push({
                id: children[i].dataset[identifier],
                children: nested ? serialize(nested) : []
            });
        }
        return serialized
    }
    console.log(serialize(root));
});