3.0.0-alpha.4 Alpha
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Split Panel

<wa-split-panel> Since 2.0 stable

Split panels display two adjacent panels, allowing the user to reposition them.

Start
End 
<wa-split-panel>
  <div
    slot="start"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    Start
  </div>
  <div
    slot="end"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    End
  </div>
</wa-split-panel>

Examples

Initial Position

To set the initial position, use the position attribute. If no position is provided, it will default to 50% of the available space.

Start
End 
<wa-split-panel position="75">
  <div
    slot="start"
    style="
      height: 200px;
      background: var(--wa-color-surface-lowered);
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    "
  >
    Start
  </div>
  <div
    slot="end"
    style="
      height: 200px;
      background: var(--wa-color-surface-lowered);
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    "
  >
    End
  </div>
</wa-split-panel>

Initial Position in Pixels

To set the initial position in pixels instead of a percentage, use the position-in-pixels attribute.

Start
End 
<wa-split-panel position-in-pixels="150">
  <div
    slot="start"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    Start
  </div>
  <div
    slot="end"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    End
  </div>
</wa-split-panel>

Vertical

Add the vertical attribute to render the split panel in a vertical orientation where the start and end panels are stacked. You also need to set a height when using the vertical orientation.

Start
End 
<wa-split-panel vertical style="height: 400px;">
  <div
    slot="start"
    style="height: 100%; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    Start
  </div>
  <div
    slot="end"
    style="height: 100%; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    End
  </div>
</wa-split-panel>

Snapping

To snap panels at specific positions while dragging, add the snap attribute with one or more space-separated values. Values must be in pixels or percentages. For example, to snap the panel at 100px and 50%, use snap="100px 50%". You can also customize how close the divider must be before snapping with the snap-threshold attribute.

Start
End 
<div class="split-panel-snapping">
  <wa-split-panel snap="100px 50%">
    <div
      slot="start"
      style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
    >
      Start
    </div>
    <div
      slot="end"
      style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
    >
      End
    </div>
  </wa-split-panel>

  <div class="split-panel-snapping-dots"></div>
</div>

<style>
  .split-panel-snapping {
    position: relative;
  }

  .split-panel-snapping-dots::before,
  .split-panel-snapping-dots::after {
    content: '';
    position: absolute;
    bottom: -12px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--wa-color-neutral-fill-loud);
    transform: translateX(-3px);
  }

  .split-panel-snapping-dots::before {
    left: 100px;
  }

  .split-panel-snapping-dots::after {
    left: 50%;
  }
</style>

Disabled

Add the disabled attribute to prevent the divider from being repositioned.

Start
End 
<wa-split-panel disabled>
  <div
    slot="start"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    Start
  </div>
  <div
    slot="end"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    End
  </div>
</wa-split-panel>

Setting the Primary Panel

By default, both panels will grow or shrink proportionally when the host element is resized. If a primary panel is designated, it will maintain its size and the secondary panel will grow or shrink to fit the remaining space. You can set the primary panel to start or end using the primary attribute.

Try resizing the example below with each option and notice how the panels respond.

Start
End
None Start End 
<div class="split-panel-primary">
  <wa-split-panel>
    <div
      slot="start"
      style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
    >
      Start
    </div>
    <div
      slot="end"
      style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
    >
      End
    </div>
  </wa-split-panel>

  <wa-select label="Primary Panel" value="" style="max-width: 200px; margin-top: 1rem;">
    <wa-option value="">None</wa-option>
    <wa-option value="start">Start</wa-option>
    <wa-option value="end">End</wa-option>
  </wa-select>
</div>

<script>
  const container = document.querySelector('.split-panel-primary');
  const splitPanel = container.querySelector('wa-split-panel');
  const select = container.querySelector('wa-select');

  select.addEventListener('wa-change', () => (splitPanel.primary = select.value));
</script>

Min & Max

To set a minimum or maximum size of the primary panel, use the --min and --max custom properties. Since the secondary panel is flexible, size constraints can only be applied to the primary panel. If no primary panel is designated, these constraints will be applied to the start panel.

This examples demonstrates how you can ensure both panels are at least 150px using --min, --max, and the calc() function.

Start
End 
<wa-split-panel style="--min: 150px; --max: calc(100% - 150px);">
  <div
    slot="start"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    Start
  </div>
  <div
    slot="end"
    style="height: 200px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden;"
  >
    End
  </div>
</wa-split-panel>

Nested Split Panels

Create complex layouts that can be repositioned independently by nesting split panels.

Start
Top
Bottom 
<wa-split-panel>
  <div
    slot="start"
    style="height: 400px; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden"
  >
    Start
  </div>
  <div slot="end">
    <wa-split-panel vertical style="height: 400px;">
      <div
        slot="start"
        style="height: 100%; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden"
      >
        Top
      </div>
      <div
        slot="end"
        style="height: 100%; background: var(--wa-color-surface-lowered); display: flex; align-items: center; justify-content: center; overflow: hidden"
      >
        Bottom
      </div>
    </wa-split-panel>
  </div>
</wa-split-panel>

Customizing the Divider

You can target the divider part to apply CSS properties to the divider. To add a custom handle, slot an icon into the divider slot. When customizing the divider, make sure to think about focus styles for keyboard users.

Start
End 
<wa-split-panel style="--divider-width: 20px;">
  <wa-icon slot="divider" name="grip-vertical" variant="solid"></wa-icon>
  <div
    slot="start"
    style="
      height: 200px;
      background: var(--wa-color-surface-lowered);
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    "
  >
    Start
  </div>
  <div
    slot="end"
    style="
      height: 200px;
      background: var(--wa-color-surface-lowered);
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    "
  >
    End
  </div>
</wa-split-panel>

Here's a more elaborate example that changes the divider's color and width and adds a styled handle.

Start
End 
<div class="split-panel-divider">
  <wa-split-panel>
    <wa-icon slot="divider" name="grip-vertical" variant="solid"></wa-icon>
    <div
      slot="start"
      style="
        height: 200px;
        background: var(--wa-color-surface-lowered);
        display: flex;
        align-items: center;
        justify-content: center;
        overflow: hidden;
      "
    >
      Start
    </div>
    <div
      slot="end"
      style="
        height: 200px;
        background: var(--wa-color-surface-lowered);
        display: flex;
        align-items: center;
        justify-content: center;
        overflow: hidden;
      "
    >
      End
    </div>
  </wa-split-panel>
</div>

<style>
  .split-panel-divider wa-split-panel {
    --divider-width: 4px;
  }

  .split-panel-divider wa-split-panel::part(divider) {
    background-color: var(--wa-color-red-50);
  }

  .split-panel-divider wa-icon {
    position: absolute;
    border-radius: var(--wa-border-radius-l);
    background: var(--wa-color-red-50);
    color: white;
    padding: 0.5rem 0.25rem;
  }

  .split-panel-divider wa-split-panel::part(divider):focus-visible {
    background-color: var(--wa-color-blue-50);
  }

  .split-panel-divider wa-split-panel:focus-within wa-icon {
    background-color: var(--wa-color-blue-50);
    color: white;
  }
</style>

Slots

Name Description
start Content to place in the start panel.
end Content to place in the end panel.
divider The divider. Useful for slotting in a custom icon that renders as a handle.

Properties

Name Description Reflects
position
position
The current position of the divider from the primary panel's edge as a percentage 0-100. Defaults to 50% of the container's initial size.
Type number
Default 50
positionInPixels
position-in-pixels
The current position of the divider from the primary panel's edge in pixels.
Type number
vertical
vertical
Draws the split panel in a vertical orientation with the start and end panels stacked.
Type boolean
Default false
disabled
disabled
Disables resizing. Note that the position may still change as a result of resizing the host element.
Type boolean
Default false
primary
primary
If no primary panel is designated, both panels will resize proportionally when the host element is resized. If a primary panel is designated, it will maintain its size and the other panel will grow or shrink as needed when the host element is resized.
Type 'start' | 'end' | undefined
snap
snap
One or more space-separated values at which the divider should snap. Values can be in pixels or percentages, e.g. "100px 50%".
Type string | undefined
snapThreshold
snap-threshold
How close the divider must be to a snap point until snapping occurs.
Type number
Default 12

Events

Name Description
wa-reposition Emitted when the divider's position changes.

CSS custom properties

Name Description
--divider-color
The color of the divider.
--divider-width
The width of the visible divider.
Default 4px
--divider-hit-area
The invisible region around the divider where dragging can occur. This is usually wider than the divider to facilitate easier dragging.
Default 12px
--min
The minimum allowed size of the primary panel.
Default 0
--max
The maximum allowed size of the primary panel.
Default 100%

CSS parts

Name Description
start The start panel.
end The end panel.
panel Targets both the start and end panels.
divider The divider that separates the start and end panels.

Importing

The autoloader is the recommended way to import components. If you prefer to do it manually, use one of the following code snippets.

CDN npm React

To manually import this component from the CDN, use the following code.

import 'https://early.webawesome.com/webawesome@3.0.0-alpha.4/dist/components/split-panel/split-panel.js';
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