Layer: Layer

LayerR Documentation



A Layer is a technical component that does not have specific Design guidance.

Layers are used to render content outside of a DOM tree, at the end of the document. This allows content to escape traditional boundaries caused by "overflow: hidden" css rules and keeps it on the top without using z-index rules. This is useful for example in ContextualMenu and Tooltip scenarios, where the content should always overlay everything else.

There are some special considerations. Due to the nature of rendering content elsewhere asynchronously, React refs within content will not be resolvable synchronously at the time the Layer is mounted. Therefore, to use refs correctly, use functional refs ref={ (el) => { this._root = el; } rather than string refs ref='root'. Additionally measuring the physical Layer element will not include any of the children, since it won't render it. Events that propgate from within the content will not go through the Layer element as well.

For more details and examples visit the official docs. The R package can not handle each and every case, so for advanced use cases you need to work using the original docs to achieve the desired result.






Props to pass to shiny.react::reactElement. See allowed props listed below in Details section


  • className string
    Additional css class to apply to the Layer

  • componentRef IRefObject<ILayer>
    Optional callback to access the ILayer interface. Use this instead of ref for accessing the public methods and properties of the component.

  • eventBubblingEnabled boolean
    When enabled, Layer allows events to bubble up from Layer content. Traditionally Layer has not had this behavior. This prop preserves backwards compatibility by default while allowing users to opt in to the new event bubbling functionality.

  • hostId string
    The optional id property provided on a LayerHost that this Layer should render within. The LayerHost does not need to be immediately available but once has been rendered, and if missing, we'll avoid trying to render the Layer content until the host is available. If an id is not provided, we will render the Layer content in a fixed position element rendered at the end of the document.

  • insertFirst boolean
    Whether the layer should be added as the first child of the host. If true, the layer will be inserted as the first child of the host By default, the layer will be appended at the end to the host

  • onLayerDidMount () => void
    Callback for when the layer is mounted.

  • onLayerMounted () => void
    Callback for when the layer is mounted.

  • onLayerWillUnmount () => void
    Callback for when the layer is unmounted.

  • styles IStyleFunctionOrObject<ILayerStyleProps, ILayerStyles>
    Call to provide customized styling that will layer on top of the variant rules

  • theme ITheme
    Theme provided by HOC.



if (interactive()) {
    ui = div(
      style = "margin-top: 60px; border: 1px solid navy; padding: 10px; background: #eee;",
      Checkbox.shinyInput("useLayer", value = FALSE, label = "Display a message in a layer"),
    server = function(input, output) {
      output$layer <- renderReact({
        box <- div(
          style = "background-color: #60C7FF; margin: 10px; padding: 10px",
        if (isTRUE(input$useLayer)) Layer(box)

if (interactive()) {
    ui = div(
      LayerHost(id = "host", style = list(border = "1px dashed", padding = 10)),
      "Layer children are rendered in the LayerHost",
      Layer(hostId = "host", "Content")
    server = function(input, output) {}

Appsilon/shiny.fluent documentation built on June 12, 2022, 2:41 a.m.