Expression to evaluate when a new partial is loaded.
                 <div class="alert alert-warning">
                 **Note:** When using onload on SVG elements in IE11, the browser will try to call
                 a function with the name on the window element, which will usually throw a
                 "function is undefined" error. To fix this, you can instead use `data-onload` or a
                 different form that matches `onload`.
                 </div>