I am using w2ui. I have a toolbar with one button. This button has the icon-image "icon-delete".
When I click on the button, I want it to change the icon-image to "icon-add", but my code doesn't work.
toolbar: {
    items: [{
        type: 'button',
        id: 'hide',
        caption: 'Menü',
        img: 'icon-delete'
    }],
    onClick: function (target, data) {
        if (target == 'hide') {
            this.items.img('icon-add');
        }
    }
}