Show different content per breakpoint

Use responsive when-xs, when-md, when-lg attributes to swap components at breakpoints.

A client list should show a full Table on desktop (≥ 768 px) and a card-based List on phones (< 768 px). Both components sit in the markup; when-* attributes mount or unmount them at the appropriate breakpoints without any JavaScript.

<App var.clients="{[
    {name:'Acme Corp', status:'Active'},
    {name:'Globex Ltd', status:'Pending'},
    {name:'Initech', status:'Active'},
    {name:'Umbrella Co', status:'Inactive'},
    {name:'Hooli', status:'Active'}
]}">
  <H3 fontSize="$fontSize-base" fontSize-md="$fontSize-xl">Client List</H3>
  <!-- visible on tablets and above (≥ 768 px) -->
  <Table data="{clients}" when-md>
    <Column bindTo="name" header="Name" />
    <Column bindTo="status" header="Status" />
  </Table>
  <!-- visible on phones only (xs and sm, below 768 px) -->
  <List data="{clients}" when-md="false">
    <property name="itemTemplate">
      <Card title="{$item.name}">
        <Badge value="{$item.status}" />
      </Card>
    </property>
  </List>
</App>

<App var.clients="{[
    {name:'Acme Corp', status:'Active'},
    {name:'Globex Ltd', status:'Pending'},
    {name:'Initech', status:'Active'},
    {name:'Umbrella Co', status:'Inactive'},
    {name:'Hooli', status:'Active'}
]}">
  <H3 fontSize="$fontSize-base" fontSize-md="$fontSize-xl">Client List</H3>
  <!-- visible on tablets and above (≥ 768 px) -->
  <Table data="{clients}" when-md>
    <Column bindTo="name" header="Name" />
    <Column bindTo="status" header="Status" />
  </Table>
  <!-- visible on phones only (xs and sm, below 768 px) -->
  <List data="{clients}" when-md="false">
    <property name="itemTemplate">
      <Card title="{$item.name}">
        <Badge value="{$item.status}" />
      </Card>
    </property>
  </List>
</App>

Key points

when-md shows an element at ≥ 768 px and hides it below: The shorthand when-md (no value) is equivalent to when-md="true". Because no rule is defined below md, the framework infers the base visibility as the opposite — hidden. A single attribute is all you need for a "desktop-only" element:

when-md="false" hides at ≥ 768 px and shows below: The framework infers the base visibility as the opposite of false, so the element is visible below md without any extra attribute. This is the cleanest way to declare a "mobile-only" element:

<!-- desktop only: visible at ≥ 768 px, hidden below -->
<Table when-md>…</Table>

<!-- mobile only: hidden at ≥ 768 px, visible below -->
<List when-md="false">…</List>

The active value is resolved by walking downward from the current breakpoint: At any viewport width, XMLUI checks when-{current}, then when-{one smaller}, and so on, using the first defined value it finds. This means when-sm="true" also covers md, lg, and xl unless a larger breakpoint provides an override.

Targeting a specific breakpoint range: Combine a truthy lower bound with a falsy upper bound to show an element only within a range:

<!-- visible only between sm and lg -->
<Text when="false" when-sm="true" when-xl="false" value="Tablet only" />

Layout-property breakpoints: Properties like fontSize, padding, and width accept -{breakpoint} suffixes. The base value applies at all sizes; a breakpoint-suffixed value overrides it from that minimum width upward:

<H3 fontSize="$fontSize-base" fontSize-md="$fontSize-xl">Client List</H3>
<VStack width-md="50%">…</VStack>

See also

• Visibility — full when-* resolution rules, inference, and breakpoint range patterns
• Layout Properties — breakpoint-suffixed sizing properties
• Table component — columns and sorting
• List component — item templates