Is loading

Table gives a isLoading state property to help with transitions.

<Datatable {table}>
    <div class="spinner" class:active={table.isLoading}></div>
    <table>
        [...]
    </table>
</Datatable>

<style>
    div.spinner {
        display: none;
    }
    div.spinner.active {
        display: block;
    }
</style>