Fade In/Out

When button is clicked, it ...
<button type="button"
    data-as='{
        "click": {
            "load": {
                "url": "./data/partial_content.html",
                "block": true,
                "blockOptions": {
                    "message": "<h2>Custom loading message</h2>"
                },
                "success": {
                    "html": {
                        "target": "#div"
                    }
                }
            }
        }
    }'
>Load content</button>

<div id="div"></div>