@spectrum-web-components/overlay

Description

An `` element is used to decorate content that you would like to present to your visitors as "overlaid" on the rest of the application. This includes dialogs (modal and not), pickers, tooltips, context menus, et al.

Usage

yarn add @spectrum-web-components/overlay

Import the side effectful registration of `` as follows:

import '@spectrum-web-components/overlay/sp-overlay.js';

When looking to leverage the Overlay base class as a type and/or for extension purposes, do so via:

import {
    Overlay
} from '@spectrum-web-components/overlay';

Example

By leveraging the trigger attribute to pass an ID reference to another element with in the same DOM tree, your overlay will be positioned in relation to this element. When the ID reference is followed by an @ symbol and interaction type, like click, hover, or longpress, the overlay will bind itself to the referenced element via the DOM events associated with that interaction. For example, the below has an id of `trigger`, and the is provided the trigger attribute with the value trigger@click. This creates an association between the overlay and the `` that opens the overlay when the button is clicked.

Overlay Trigger



    
        
            <h2 slot="heading">Clicking opens this popover...</h2>
            <p>But, it really could be anything. Really.</p>
        
    




    
        I'm a tooltip and I'm triggered by hovering over the button!
    

When a element is opened, it will pass that state to its direct children elements as the property `open`, which it will set to `true`. Elements should react to this by initiating any transition between closed and open that they see fit. Similarly, `open` will be set to `false` when the element is closed.

Action Bar

<style>
    .overlay-demo-popover sp-action-group {
        padding: var(--spectrum-actiongroup-vertical-spacing-regular);
    }
    #overlay-demo {
        position: static;
    }
    #overlay-demo:not(:defined),
    #overlay-demo *:not(:defined) {
        display: none;
    }
</style>

    
        
            
        
        
            
        
        
            
        
    
    
        Hover
    
    
        
            
                
                    
                
                
                    
                
                
                    
                
            
        
    
    
        Hover
    
    
        
            
                
                    
                
                
                    
                
                
                    
                
            
        
    
    
        Hover
    
    
        
            
                
                    
                
                
                    
                
                
                    
                
            
        
    

API

API value interactions

When a triggerElement is present, either through an ID reference established via the trigger attribute or by directly setting the triggerElement property, a chain on configuration begins:

• if a triggerInteraction is available, either through the id@interaction IDL on the trigger attribute or directly setting the triggerInteraction property, the `` will be bound to the resolved triggerElement via the triggerInteraction provided
• if a placement is available when the `` is open and displaying its contents, those contents will be positioned relative to the triggerElement as per that placement
  • if an offset is also available the `` will distance itself from the triggerElement in accordance with the value of the offset
  • if you have a placement but not a triggerElement the `` will not be positioned due to their being nothing for the placement to reference when so doing
• if no placement is available the content will not be placed with the expectation that the content itself or the consuming application will handle placement of the overlaid content. This is commonly what will happen for type="modal" and type="page" overlays as they are likely meant to cover the entire screen, whether visibly (via an ``, an element that includes one, or similar) or figuratively (as when modal content is not delivered with a backdrop or scrim).

Overlay types

The type of an Overlay outlines a number of things about the interaction model within which is works.

Modal

'modal' Overlays are opened with the showModal() method on a <dialog> element, which causes the Overlay to accept focus and trap the tab stop within the content of said Overlay.

They should be used when you need to ensure that the user has interacted with the content of the Overlay before continuing with their work. This is commonly used for dialogs that require a user to confirm or cancel an action before continuing.

open modal

    
        <p>I am a modal type overlay.</p>
        Enter your email
        
        
            Sign in
        
    

Page

'page' Overlays will act in a similar manner to a 'modal' Overlay, however they will not be allowed to close via the "light dismiss" algorithm (e.g. the Escape key).

A page overlay could be used for a full-screen menu on a mobile website. When the user clicks on the menu button, the entire screen is covered with the menu options.

open page

    
        <p>I am a page type overlay.</p>
    

Hint

'hint' Overlays are much like tooltips so they are not just ephemeral, but they are delivered primarily as a visual helper and exist outside of the tab order. In this way, be sure not to place interactive content within this type of Overlay.

This overlay type does not accept focus and does not interfere with the user's interaction with the rest of the page.

open hint

    
        I am a hint type overlay. I am not interactive and will close when the
        user interacts with the page.
    

Auto

'auto' Overlays provide a place for content that is ephemeral and interactive. These Overlays can accept focus but will close when losing that focus, or when interacting with other parts of the page.

<style>
    sp-toast {
        position: fixed;
        top: 1em;
        right: 1em;
    }
</style>
open auto

    
        This is information that you should read.
    

Manual

'manual' Overlays act much like 'auto' Overlays, but do not close when losing focus or interacting with other parts of the page.

Note: When a 'manual' Overlay is at the top of the "overlay stack", it will still respond to the Escape key and close.

<style>
    .chat-container {
        position: fixed;
        bottom: 1em;
        left: 1em;
    }
</style>
open manual

    
        
            <span slot="heading">Chat Window</span>
            
            Send
        
    

Events

When fully open the `` element will dispatch the sp-opened event, and when fully closed the sp-closed event will be dispatched. Both of these events are of type:

type OverlayStateEvent = Event & {
    overlay: Overlay;
};

The overlay value in this case will hold a reference to the actual that is opening or closing to trigger this event. Remember that some element (like those creates via the imperative API) can be transiently available in the DOM, so if you choose to build a cache of Overlay elements to some end, be sure to leverage a weak reference so that the `` can be garbage collected as desired by the browser.

When it is "fully" open or closed?

"Fully" in this context means that all CSS transitions that have dispatched transitionrun events on the direct children of the `` element have successfully dispatched their transitionend or transitioncancel event. Keep in mind the following:

• transition* events bubble; this means that while transition events on light DOM content of those direct children will be heard, those events will not be taken into account
• transition* events are not composed; this means that transition events on shadow DOM content of the direct children will not propagate to a level in the DOM where they can be heard

This means that in both cases, if the transition is meant to be a part of the opening or closing of the overlay in question you will need to redispatch the transitionrun, transitionend, and transitioncancel events from that transition from the closest direct child of the ``.

Styling

`` element will use the <dialog> element or popover attribute to project your content onto the top-layer of the browser, without being moved in the DOM tree. That means that you can style your overlay content with whatever techniques you are already leveraging to style the content that doesn't get overlaid. This means standard CSS selectors, CSS Custom Properties, and CSS Parts applied in your parent context will always apply to your overlaid content.

Top Layer over Complex CSS

There are some complex CSS values that have not yet been covered by the positioning API that the `` element leverages to associate overlaid content with their trigger elements. In specific, properties like filter, when applied to a trigger element within which lives the related content to be overlaid, are not currently supported by the relationship created herein. If support for this is something that you and the work you are addressing would require, we'd love to hear from you in an issue. We'd be particularly interested in speaking with you if you were interested in contributing support/testing to ensure this capability for all consumers of the library.

Fallback support

While the <dialog> element is widely supported by browsers, the popover attribute is still quite new. When leveraged in browsers that do not yet support the popover attribute, there may be additional intervention required to ensure your content is delivered to your visitors as expected.

Complex layered

When an overlay is placed within a page with complex layering, the content therein can fall behind other content in the z-index stack. The following example is somewhat contrived but, imagine a toolbar next to a properties panel. If the toolbar has a lower z-index than the properties panel, any overlaid content (tooltips, etc.) within that toolbar will display underneath any content in the properties panel with which it may share pixels.

<div class="complex-layered-demo">
    <div class="complex-layered-holder">
        Trigger
        
            
                I can be partially blocked when [popover] is not available
            
        
    </div>
    <div class="complex-layered-blocker"></div>
</div>
<style>
    .complex-layered-demo {
        position: relative;
    }
    .complex-layered-holder {
        z-index: 1;
        position: relative;
    }
    .complex-layered-blocker {
        position: relative;
        z-index: 10;
        background: white;
        width: 100%;
        height: 40px;
    }
</style>

Properly managed z-index values will support working around this issue while browsers work to adopt the popover attribute. In this demo, you can achieve the same output by sharing one z-index between the various pieces of content, removing z-index values altogether, or raising the .complex-layered-holder element to a higher z-index than the .complex-layered-blocker element.

Contained

CSS Containment gives a developer direct control over how the internals of one element affect the paint and layout of the internals of other elements on the same page. While leveraging some of its values can offer performance gains, they can interrupt the delivery of your overlaid content.

<div class="contained-demo">
    Trigger
    
        
            I can be blocked when [popover] is not available
        
    
</div>
<style>
    .contained-demo {
        contain: content;
    }
</style>

You could just remove the contain rule. But, if you are not OK with simply removing the contain value, you still have options. If you would like to continue to leverage contain, you can place your "contained" content separately from your overlaid content, like so:

<div class="contained-demo">
    Trigger
</div>

    I can be blocked when [popover] is not available

<style>
    .contained-demo {
        contain: content;
    }
</style>

accepts an ID reference via the `trigger` attribute to relate it to interactions and positioning in the DOM. To fulfill this reference the two elements need to be in the same DOM tree. However, alternatively accepts a triggerElement property that opens even more flexibility in addressing this situation.

Clip pathed

clip-path can also restrict how content in an element is surfaced at paint time. When overlaid content should display outside of the clip-path, without the popover attribute, that content could be clipped.

<div class="clip-pathed-demo">
    Trigger
    
        
            I can be blocked when [popover] is not available
        
    
</div>
<style>
    .clip-pathed-demo {
        clip-path: inset(0 0);
    }
</style>

Here, again, working with your content needs (whether or not you want to leverage clip-path) or DOM structure (not colocating clipped and non-clipped content) will allow you to avoid this issue:

<div class="clip-pathed-demo">
    Trigger
</div>

    I can be blocked when [popover] is not available

<style>
    .clip-pathed-demo {
        clip-path: inset(0 0);
    }
</style>

Non-overflowing, relative containers with z-index in Safari

Under very specific conditions, WebKit will incorrectly clip fixed-position content. WebKit clips position: fixed elements within containers that have all of:

1. position: relative
2. overflow: clip or overflow: hidden
3. z-index greater than zero

If you notice overlay clipping only in Safari, this is likely the culprit. The solution is to break up the conditions into separate elements to avoid triggering WebKit's bug. For example, leaving relative positioning and z-index on the outermost container while creating an inner container that enforces the overflow rules.