This example loads a PDF that contains several optional content layers with visibility depending on the current viewer zoom. Change the zoom factor to see the viewer automatically switch layers.
window.onload = function(){
//DsPdfViewer.LicenseKey = "***key***";
const viewer = new DsPdfViewer("#viewer");
viewer.toolbarLayout.viewer.mobile = viewer.toolbarLayout.viewer.default = ["open", "zoom", "download", "about"];
const layersPanelHandle = viewer.addLayersPanel();
viewer.open("/document-solutions/javascript-pdf-viewer/demos/product-bundles/assets/pdf/zoom-layers.pdf").then(()=> {
viewer.leftSidebar.menu.panels.open(layersPanelHandle.id)
viewer.leftSidebar.menu.panels.pin(layersPanelHandle.id);
});
}