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Notification

Source: TypeScript / Java
Notification is used to provide feedback to the user about activities, processes, and events in the application.

Notification is used to provide feedback to the user about activities, processes, and events in the application.

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const notification = Notification.show('Financial report generated', {
  position: 'middle',
  duration: 0,
});

Theme Variants

Notification comes with a few theme variants: success; warning; error; primary; and contrast. These variants are described in the following sub-sections:

Success

The success theme variant can be used to display success messages, such as when a task or operation is completed.

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const notification = Notification.show('Application submitted!', {
  position: 'middle',
  duration: 0,
  theme: 'success',
});

Users shouldn’t be notified always, or even frequently, of successful operations. Too many notifications can be more distracting than helpful to users. Use success notifications only for operations whose successful completion may otherwise be difficult to discern.

Warning

The warning theme variant can be used to display warnings.

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<!-- The duration is set to 0-sec to prevent the notification from auto-close. -->
<vaadin-notification
  theme="warning"
  duration="0"
  position="middle"
  .opened="${this.notificationOpened}"
  @opened-changed="${(e: NotificationOpenedChangedEvent) => {
    this.notificationOpened = e.detail.value;
  }}"
  ${notificationRenderer(this.renderer, [])}
></vaadin-notification>

<!-- ... -->

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout theme="spacing" style="align-items: center;">
    <div>
      Your session will expire in 5 minutes due to inactivity.<br />
      Close this warning to continue working.
    </div>
    <vaadin-button theme="tertiary-inline" @click="${this.close}" aria-label="Close">
      <vaadin-icon icon="lumo:cross"></vaadin-icon>
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

Warning notifications should be persistent, and provide the user with a button that closes the notification or allows the user to take appropriate action.

Error

The error theme variant can be used to display errors.

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<!-- The duration is set to 0-sec to prevent the notification from auto-close. -->
<vaadin-notification
  theme="error"
  duration="0"
  position="middle"
  .opened="${this.notificationOpened}"
  @opened-changed="${(e: NotificationOpenedChangedEvent) => {
    this.notificationOpened = e.detail.value;
  }}"
  ${notificationRenderer(this.renderer, [])}
></vaadin-notification>

<!-- ... -->

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout theme="spacing" style="align-items: center;">
    <div>Failed to generate report</div>
    <vaadin-button theme="tertiary-inline" @click="${this.close}" aria-label="Close">
      <vaadin-icon icon="lumo:cross"></vaadin-icon>
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

Error notifications should be persistent, and provide the user with a button that closes the notification or allows the user to take appropriate action.

Notifications are non-modal and can be ignored. Therefore, they’re usually inappropriate for displaying unexpected technical errors that prevent the application from functioning, or situations that require immediate user action. Use instead a modal Dialog in such situations.

The built-in error message feature, included with input field components, should be used for field-specific input validation errors.

Primary

The primary theme variant can be used for important informational messages or to draw extra attention to a notification.

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const notification = Notification.show('New project plan available', {
  position: 'middle',
  duration: 0,
  theme: 'primary',
});

Contrast

The contrast variant can improve legibility and distinguish the notification from the rest of the UI.

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const notification = Notification.show('5 tasks deleted', {
  position: 'middle',
  duration: 0,
  theme: 'contrast',
});

Duration

By default, notifications stay on-screen for five seconds. The duration can be set — in milliseconds — and should be done so based on the content and its importance:

  • Use short durations for notifications that contain short text, are of lesser importance (e.g., operations that finished without errors), and have no interactive elements.

  • Use longer durations for notifications that contain longer text, are of higher importance (e.g., errors), and have interactive elements (e.g., links or "undo" actions).

A duration of at least five seconds (i.e., 5000 milliseconds) is recommended — this is why it’s the default — to ensure that the user has a chance to read and understand the notification.

Persistent Notifications

Setting the duration to 0 milliseconds disables auto-closing. It keeps the notification visible until it’s explicitly dismissed by the user. This should be used for notifications that provide vital information to the user, such as errors.

Persistent notifications should contain a Button that closes the notification, or allows the user to take appropriate action. Less-important notifications shouldn’t be persistent, and instead disappear automatically after an appropriate delay.

Position

Notifications can be positioned in the viewport in seven non-stretched positions, or stretched across the top or bottom:

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Use the position attribute in HTML templates (e.g., <vaadin-notification position="top-end"></vaadin-notification>).

protected override render() {
  return html`
    <vaadin-button @click="${this.show}">top-stretch</vaadin-button>
    <vaadin-button @click="${this.show}">top-start</vaadin-button>
    <vaadin-button @click="${this.show}">top-center</vaadin-button>
    <vaadin-button @click="${this.show}">top-end</vaadin-button>
    <vaadin-button @click="${this.show}">middle</vaadin-button>
    <vaadin-button @click="${this.show}">bottom-start</vaadin-button>
    <vaadin-button @click="${this.show}">bottom-center</vaadin-button>
    <vaadin-button @click="${this.show}">bottom-end</vaadin-button>
    <vaadin-button @click="${this.show}">bottom-stretch</vaadin-button>
  `;
}

show(event: MouseEvent) {
  // Use the button label as the location
  const position = (event.target as HTMLElement).textContent as NotificationPosition;

  Notification.show(position, { position });
}

Top End or Bottom Start are recommended for most notifications. They’re unobtrusive, but still noticeable. Middle is the most disruptive position, and should be used only for important notifications, such as errors. Bottom End is the least obtrusive position, but can go unnoticed. Stretch notifications, which span the full width of the viewport, are disruptive, and should be reserved for important notifications whose content requires more space.

Applications with a notification button, or a drop-down in the header or footer, should position notifications to appear in the same part of the screen. For a consistent user experience, use one or two positions throughout the application. Avoid using positions that may obstruct important parts of the UI, such as navigation.

Stacking

Multiple simultaneously displayed notifications are stacked vertically. The ordering of them, though, depends on their positioning.

When using the bottom half of the screen as the position, a new notification appears below the older notifications. With the position set to the top half, a new notification appears above the existing notifications.

Size

The notification card is automatically sized based on its content.

In large viewports, the card’s maximum width is one-third of the viewport. In small viewports, the card always consumes the entire width of the viewport.

Interactive Elements

Notifications can contain interactive content (e.g., Buttons or links) that allow the user to perform related actions.

For example, if an operation fails, the error notification could offer the user the opportunity to try again. Or it could contain a link to a view that allows the user to resolve the problem.

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<!-- The duration is set to 0-sec to prevent the notification from auto-close. -->
<vaadin-notification
  theme="error"
  duration="0"
  position="middle"
  .opened="${this.notificationOpened}"
  @opened-changed="${(e: NotificationOpenedChangedEvent) => {
    this.notificationOpened = e.detail.value;
  }}"
  ${notificationRenderer(this.renderer, [])}
></vaadin-notification>

<!-- ... -->

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout theme="spacing" style="align-items: center;">
    <div>Failed to generate report</div>
    <vaadin-button
      theme="tertiary-inline"
      style="margin-left: var(--lumo-space-xl);"
      @click="${this.close}"
    >
      Retry
    </vaadin-button>
    <vaadin-button theme="tertiary-inline icon" @click="${this.close}" aria-label="Close">
      <vaadin-icon icon="lumo:cross"></vaadin-icon>
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

In situations where the user might want to revert an action, display an "Undo" button.

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<vaadin-notification
  theme="contrast"
  duration="10000"
  position="middle"
  .opened="${this.notificationOpened}"
  @opened-changed="${(e: NotificationOpenedChangedEvent) => {
    this.notificationOpened = e.detail.value;
  }}"
  ${notificationRenderer(this.renderer, [])}
></vaadin-notification>

<!-- ... -->

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout theme="spacing" style="align-items: center;">
    <div>5 tasks deleted</div>
    <vaadin-button
      theme="tertiary-inline"
      style="margin-left: var(--lumo-space-xl);"
      @click="${this.close}"
    >
      Undo
    </vaadin-button>
    <vaadin-button theme="tertiary-inline" aria-label="Close" @click="${this.close}">
      <vaadin-icon icon="lumo:cross"></vaadin-icon>
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

Notifications can also contain links to relevant information.

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<!-- The duration is set to 0-sec to prevent the notification from auto-close. -->
<vaadin-notification
  duration="0"
  position="middle"
  .opened="${this.notificationOpened}"
  @opened-changed="${(e: NotificationOpenedChangedEvent) => {
    this.notificationOpened = e.detail.value;
  }}"
  ${notificationRenderer(this.renderer, [])}
></vaadin-notification>

<!-- ... -->

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout theme="spacing" style="align-items: center;">
    <div>Jason Bailey mentioned you in <a href="#">Project Q4</a></div>
    <vaadin-button theme="tertiary-inline" aria-label="Close" @click="${this.close}">
      <vaadin-icon icon="lumo:cross"></vaadin-icon>
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

Keyboard-Accessible

Make sure that keyboard-only users can access interactive elements in notifications.

Make the notification persistent to prevent it from disappearing before the user has had a chance to react. Provide a keyboard shortcut — either to trigger the action itself or to move focus to the notification card — in cases where multiple interactive elements are present. Finally, make the shortcut discoverable, for example, by displaying it as part of the notification’s content.

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protected override render() {
  return html`
    <vaadin-notification
      theme="contrast"
      duration="10000"
      position="middle"
      .opened="${this.notificationOpened}"
      @opened-changed="${(e: NotificationOpenedChangedEvent) => {
        this.notificationOpened = e.detail.value;
      }}"
      ${notificationRenderer(this.renderer, [])}
    ></vaadin-notification>
  `;
}

renderer: NotificationLitRenderer = () => html`
  <vaadin-horizontal-layout style="align-items: center;">
    <div>5 tasks deleted</div>
    <vaadin-button
      style="margin-left: var(--lumo-space-xl);"
      theme="primary"
      @click="${this.close}"
    >
      Undo
      <!-- Ideally, this should be hidden if the
               device does not have a physical keyboard -->
      ${this.isMac ? '⌘' : 'Ctrl-'}Z
    </vaadin-button>
  </vaadin-horizontal-layout>
`;

connectedCallback() {
  super.connectedCallback();

  document.addEventListener('keydown', this.onKeyDown);
}

disconnectedCallback() {
  super.disconnectedCallback();

  document.removeEventListener('keydown', this.onKeyDown);
}

onKeyDown = (event: KeyboardEvent) => {
  if (this.notificationOpened && (event.metaKey || event.ctrlKey) && event.key === 'z') {
    // Handle your custom undo logic here
    // Avoid triggering the native undo action
    event.preventDefault();
    this.close();
  }
};

Icons & Other Rich Formatting

Icons and other content formatting can be used to provide information and helpful visual cues. For example, you might do this to make error and success notifications easier to distinguish for users with color blindness.

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import '@vaadin/avatar';
import '@vaadin/button';
import '@vaadin/icon';
import '@vaadin/icons';
import '@vaadin/notification';
import '@vaadin/vaadin-lumo-styles/vaadin-iconset';
import { html, LitElement } from 'lit';
import { customElement } from 'lit/decorators.js';
import { applyTheme } from 'Frontend/generated/theme';

@customElement('notification-rich-preview')
export class Example extends LitElement {
  protected override createRenderRoot() {
    const root = super.createRenderRoot();
    // Apply custom theme (only supported if your app uses one)
    applyTheme(root);
    return root;
  }

  protected override render() {
    return html`
      <vaadin-notification-card theme="success" slot="middle">
        <vaadin-horizontal-layout theme="spacing" style="align-items: center">
          <vaadin-icon icon="vaadin:check-circle"></vaadin-icon>
          <div>Application submitted!</div>
          <vaadin-button style="margin: 0 0 0 var(--lumo-space-l)">View</vaadin-button>
          <vaadin-button theme="tertiary-inline">
            <vaadin-icon icon="lumo:cross"></vaadin-icon>
          </vaadin-button>
        </vaadin-horizontal-layout>
      </vaadin-notification-card>

      <vaadin-notification-card theme="error" slot="middle">
        <vaadin-horizontal-layout theme="spacing" style="align-items: center">
          <vaadin-icon icon="vaadin:warning"></vaadin-icon>
          <div>Failed to generate report</div>
          <vaadin-button style="margin: 0 0 0 var(--lumo-space-l)">Retry</vaadin-button>
          <vaadin-button theme="tertiary-inline">
            <vaadin-icon icon="lumo:cross"></vaadin-icon>
          </vaadin-button>
        </vaadin-horizontal-layout>
      </vaadin-notification-card>

      <vaadin-notification-card slot="middle">
        <vaadin-horizontal-layout theme="spacing" style="align-items: center">
          <vaadin-avatar name="Jason Bailey"></vaadin-avatar>
          <div><b>Jason Bailey</b> mentioned you in <a href="#">Project Q4</a></div>
          <vaadin-button theme="tertiary-inline">
            <vaadin-icon icon="lumo:cross"></vaadin-icon>
          </vaadin-button>
        </vaadin-horizontal-layout>
      </vaadin-notification-card>

      <vaadin-notification-card slot="middle">
        <vaadin-horizontal-layout theme="spacing" style="align-items: center">
          <vaadin-icon
            icon="vaadin:check-circle"
            style="color: var(--lumo-success-color)"
          ></vaadin-icon>
          <div>
            <b style="color: var(--lumo-success-text-color);">Upload successful</b>
            <div
              style="font-size: var(--lumo-font-size-s); color: var(--lumo-secondary-text-color);"
            >
              <b>Financials.xlsx</b> is now available in <a href="#">Documents</a>
            </div>
          </div>
          <vaadin-button theme="tertiary-inline">
            <vaadin-icon icon="lumo:cross"></vaadin-icon>
          </vaadin-button>
        </vaadin-horizontal-layout>
      </vaadin-notification-card>
    `;
  }
}
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<vaadin-notification
  ${notificationRenderer(
    (notification) => html`
      <vaadin-horizontal-layout theme="spacing" style="align-items: center">
        <vaadin-icon icon="vaadin:check-circle"></vaadin-icon>
        <div>Application submitted!</div>
        <vaadin-button
          style="margin: 0 0 0 var(--lumo-space-l)"
          @click="${() => notification.close()}"
        >
          View
        </vaadin-button>
        <vaadin-button
          theme="tertiary-inline"
          @click="${() => notification.close()}"
          aria-label="Close"
        >
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-horizontal-layout>
    `,
    []
  )}
  theme="success"
  position="middle"
></vaadin-notification>

<vaadin-notification
  ${notificationRenderer(
    (notification) => html`
      <vaadin-horizontal-layout theme="spacing" style="align-items: center">
        <vaadin-icon icon="vaadin:warning"></vaadin-icon>
        <div>Failed to generate report</div>
        <vaadin-button
          style="margin: 0 0 0 var(--lumo-space-l)"
          @click="${() => notification.close()}"
        >
          Retry
        </vaadin-button>
        <vaadin-button
          theme="tertiary-inline"
          @click="${() => notification.close()}"
          aria-label="Close"
        >
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-horizontal-layout>
    `,
    []
  )}
  theme="error"
  position="middle"
></vaadin-notification>

<vaadin-notification
  ${notificationRenderer(
    (notification) => html`
      <vaadin-horizontal-layout theme="spacing" style="align-items: center">
        <vaadin-avatar name="Jason Bailey"></vaadin-avatar>
        <div><b>Jason Bailey</b> mentioned you in <a href="#">Project Q4</a></div>
        <vaadin-button
          theme="tertiary-inline"
          @click="${() => notification.close()}"
          aria-label="Close"
        >
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-horizontal-layout>
    `,
    []
  )}
  position="middle"
></vaadin-notification>

<vaadin-notification
  ${notificationRenderer(
    (notification) => html`
      <vaadin-horizontal-layout theme="spacing" style="align-items: center">
        <vaadin-icon
          icon="vaadin:check-circle"
          style="color: var(--lumo-success-color)"
        ></vaadin-icon>
        <div>
          <b style="color: var(--lumo-success-text-color);">Upload successful</b>
          <div
            style="font-size: var(--lumo-font-size-s); color: var(--lumo-secondary-text-color)"
          >
            <b>Financials.xlsx</b> is now available in <a href="#">Documents</a>
          </div>
        </div>
        <vaadin-button
          theme="tertiary-inline"
          @click="${() => notification.close()}"
          aria-label="Close"
        >
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-horizontal-layout>
    `,
    []
  )}
  position="middle"
></vaadin-notification>

Static Helper

For simple, one-off notifications, it’s convenient to use the static show() helper method. The helper manages the notification’s lifecycle, and adds and removes it from the DOM, automatically.

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// Show a simple text-based notification
Notification.show('Financial report generated', {
  position: 'middle',
});
// Show a notification with markup using a Lit template
Notification.show(
  html`
    <b>@John:</b>
    &nbsp;
    <span>
      How about lunch at
      <span style="color: var(--lumo-primary-text-color)">12:30pm</span>?
    </span>
  `,
  {
    position: 'middle',
  }
);

Best Practices

Use Sparingly

Notifications are disruptive by design and should be used sparingly. Use fewer notifications by reserving them for more-important information that might otherwise go unnoticed by the user.

Less-urgent notifications can be provided through a link or a drop-down in the application header or footer, instead of via immediate notifications.

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protected override render() {
  return html`
    <vaadin-context-menu
      open-on="click"
      ${contextMenuRenderer(
        () => html`<div style="padding: var(--lumo-space-l);">Show notifications here</div>`,
        []
      )}
    >
      <vaadin-button aria-label="notifications" theme="tertiary">
        <vaadin-icon icon="vaadin:bell-o"></vaadin-icon>
        <span theme="badge error primary small pill">4</span>
      </vaadin-button>
    </vaadin-context-menu>
  `;
}

Limit Content Length

Notifications should be brief and to the point. Try to limit the content to one or two lines. More information can be provided through an embedded link or Button.

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Show a preview of longer content, and link to the full details.
import '@vaadin/button';
import '@vaadin/icon';
import '@vaadin/notification';
import '@vaadin/vaadin-lumo-styles/vaadin-iconset';
import { html, LitElement } from 'lit';
import { applyTheme } from 'Frontend/generated/theme';

export class Example extends LitElement {
  protected override createRenderRoot() {
    const root = super.createRenderRoot();
    // Apply custom theme (only supported if your app uses one)
    applyTheme(root);
    return root;
  }

  protected override render() {
    return html`
      <vaadin-notification-card slot="middle">
        <div>
          <div>Aria Bailey</div>
          <div style="font-size: var(--lumo-font-size-s); color: var(--lumo-secondary-text-color);">
            Yeah, I know. But could you help me with...
          </div>
        </div>
        <vaadin-button>View</vaadin-button>
        <vaadin-button theme="tertiary-inline">
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-notification-card>
    `;
  }
}
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Don’t display all details in the notification.
import '@vaadin/button';
import '@vaadin/icon';
import '@vaadin/notification';
import '@vaadin/vaadin-lumo-styles/vaadin-iconset';
import { html, LitElement } from 'lit';
import { applyTheme } from 'Frontend/generated/theme';

export class Example extends LitElement {
  protected override createRenderRoot() {
    const root = super.createRenderRoot();
    // Apply custom theme (only supported if your app uses one)
    applyTheme(root);
    return root;
  }

  protected override render() {
    return html`
      <vaadin-notification-card slot="middle">
        <div>
          <div>New message from Aria Bailey</div>
          <div style="font-size: var(--lumo-font-size-s); color: var(--lumo-secondary-text-color);">
            Yeah, I know. But could you help me with this. I’m not sure where the bug is in my CSS?
            The checkmark doesn’t get the right color. I’m trying to use the CSS custom properties
            from our design system, but for some reason it’s not working.
          </div>
        </div>
        <vaadin-button theme="tertiary-inline">
          <vaadin-icon icon="lumo:cross"></vaadin-icon>
        </vaadin-button>
      </vaadin-notification-card>
    `;
  }
}
Component Usage Recommendation

Dialog

Dialog should be used instead of Notification for anything that requires immediate user action.

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