@material/top-app-bar/README.md

<!--docs:
title: "Top App Bar"
layout: detail
section: components
excerpt: "A container for items such as application title, navigation icon, and action items."
iconId: toolbar
path: /catalog/top-app-bar/
-->

# Top app bar

The top app bar provides content and actions related to the current screen. It’s used for branding, screen titles, navigation, and actions.

There are two types of top app bar:

1. [Regular top app bar](#regular-top-app-bar)
1. [Contextual action bar](#contextual-action-bar)

A regular top app bar can transform into a contextual action bar.

![Regular app bar: purple background, white text and icons](images/regular-app-bar.png)
![Contextual app bar: black background, white text and icons](images/contextual-app-bar.png)

## Using the top app bar

### Installation

```
npm install @material/top-app-bar
```

### Styles

```scss
@use "@material/icon-button";
@use "@material/top-app-bar/mdc-top-app-bar";

@include icon-button.core-styles;
```

### JavaScript Instantiation

```js
import {MDCTopAppBar} from '@material/top-app-bar';

// Instantiation
const topAppBarElement = document.querySelector('.mdc-top-app-bar');
const topAppBar = new MDCTopAppBar(topAppBarElement);
```

**Note: See [Importing the JS component](../../docs/importing-js.md) for more information on how to import JavaScript.**

## Regular top app bar

The top app bar provides content and actions related to the current screen. It’s used for branding, screen titles, navigation, and actions.

### Regular top app bar example

```html
<header class="mdc-top-app-bar">
  <div class="mdc-top-app-bar__row">
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-start">
      <button class="material-icons mdc-top-app-bar__navigation-icon mdc-icon-button" aria-label="Open navigation menu">menu</button>
      <span class="mdc-top-app-bar__title">Page title</span>
    </section>
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-end" role="toolbar">
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Favorite">favorite</button>
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Search">search</button>
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Options">more_vert</button>
    </section>
  </div>
</header>
<main class="mdc-top-app-bar--fixed-adjust">
  App content
</main>
```

#### Menu icons

Top app bars can contain action items which are placed on the side opposite the navigation icon. You must also attach the `mdc-icon-button` class to both the `mdc-top-app-bar__navigation-icon` and the `mdc-top-app-bar__action-item` elements in order to get the correct styles applied. 

For further documentation on icons, please see the [mdc-icon-button docs](../mdc-icon-button/README.md).

## Contextual action bar

A top app bar can transform into a contextual action bar to provide contextual actions to selected items. For example, upon user selection of photos from a gallery, the top app bar transforms to a contextual app bar with actions related to the selected photos.

When a top app bar transforms into a contextual action bar, the following changes occur:

* The bar color changes
* Navigation icon is replaced with a close icon
* Top app bar title text converts to contextual action bar text
* Top app bar actions are replaced with contextual actions
* Upon closing, the contextual action bar transforms back into a top app bar.

### Contextual action bar example

The following example shows a contextual action bar with a contextual title, a close icon, two contextual action icons, and an overflow menu:

```html
<header class="mdc-top-app-bar">
  <div class="mdc-top-app-bar__row">
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-start">
      <button class="material-icons mdc-top-app-bar__navigation-icon mdc-icon-button" aria-label="Close">close</button>
      <span class="mdc-top-app-bar__title">Contextual title</span>
    </section>
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-end" role="toolbar">
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Share">share</button>
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Delete">delete</button>
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Open menu">more_vert</button>
    </section>
  </div>
</header>
<main class="mdc-top-app-bar--fixed-adjust">
  App content
</main>
````

## Other Variants

### Short

Short top app bars are top app bars that can collapse to the navigation icon side when scrolled.

```html
<header class="mdc-top-app-bar mdc-top-app-bar--short">
  <div class="mdc-top-app-bar__row">
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-start">
      <button class="material-icons mdc-top-app-bar__navigation-icon mdc-icon-button">menu</button>
      <span class="mdc-top-app-bar__title">Title</span>
    </section>
    <section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-end" role="toolbar">
      <button class="material-icons mdc-top-app-bar__action-item mdc-icon-button" aria-label="Bookmark this page">bookmark</button>
    </section>
  </div>
</header>
<main class="mdc-top-app-bar--short-fixed-adjust">
  App content
</main>
```

**Note: Short top app bars should be used with no more than 1 action item.**

### Short - always closed

Short top app bars can be configured to always appear collapsed by applying the `mdc-top-app-bar--short-collapsed` before instantiating the component :

```html
<header class="mdc-top-app-bar mdc-top-app-bar--short mdc-top-app-bar--short-collapsed">
  ...
</header>
<main class="mdc-top-app-bar--short-fixed-adjust">
  App content
</main>
```

### Fixed

Fixed top app bars stay at the top of the page and elevate above the content when scrolled.

```html
<header class="mdc-top-app-bar mdc-top-app-bar--fixed">
  ...
</header>
<main class="mdc-top-app-bar--fixed-adjust">
  App content
</main>
```

### Prominent

The prominent top app bar is taller.

```html
<header class="mdc-top-app-bar mdc-top-app-bar--prominent">
  ...
</header>
<main class="mdc-top-app-bar--prominent-fixed-adjust">
  App content
</main>
```

### Dense

The dense top app bar is shorter.

```html
<header class="mdc-top-app-bar mdc-top-app-bar--dense">
  ...
</header>
<main class="mdc-top-app-bar--dense-fixed-adjust">
  App content
</main>
```

## Style customization

### CSS classes

Class | Description
--- | ---
`mdc-top-app-bar` | Mandatory.
`mdc-top-app-bar--fixed` | Class used to style the top app bar as a fixed top app bar.
`mdc-top-app-bar--fixed-adjust` | Class used to style the content below the top app bar to prevent the top app bar from covering it.
`mdc-top-app-bar--prominent` | Class used to style the top app bar as a prominent top app bar.
`mdc-top-app-bar--prominent-fixed-adjust` | Class used to style the content below the prominent top app bar to prevent the top app bar from covering it.
`mdc-top-app-bar--dense` | Class used to style the top app bar as a dense top app bar.
`mdc-top-app-bar--dense-fixed-adjust` | Class used to style the content below the dense top app bar to prevent the top app bar from covering it.
`mdc-top-app-bar--dense-prominent-fixed-adjust` | Class used to style the content below the top app bar when styled as both dense and prominent, to prevent the top app bar from covering it.
`mdc-top-app-bar--short` | Class used to style the top app bar as a short top app bar.
`mdc-top-app-bar--short-collapsed` | Class used to indicate the short top app bar is collapsed.
`mdc-top-app-bar--short-fixed-adjust` | Class used to style the content below the short top app bar to prevent the top app bar from covering it.

### Sass mixins

Mixin | Description
--- | ---
`ink-color($color)` | Sets the ink color of the top app bar.
`icon-ink-color($color)` | Sets the ink color of the top app bar icons.
`fill-color($color)` | Sets the fill color of the top app bar.
`fill-color-accessible($color)` | Sets the fill color of the top app bar and automatically sets a high-contrast ink color.
`short-shape-radius($radius, $rtl-reflexive)` | Sets the rounded shape to short top app bar variant (when it is collapsed) with given radius size. Set `$rtl-reflexive` to true to flip radius values in RTL context, defaults to true.

## `MDCTopAppBar` properties and methods

Method Signature | Description
--- | ---
`setScrollTarget(target: element) => void` | Sets scroll target to different DOM node (default is window).

### Events

Event Name | Event Data Structure | Description
--- | --- | ---
`MDCTopAppBar:nav` | None | Emits when the navigation icon is clicked.

## Usage within web frameworks

If you are using a JavaScript framework, such as React or Angular, you can create a Top App Bar for your framework. Depending on your needs, you can use the _Simple Approach: Wrapping MDC Web Vanilla Components_, or the _Advanced Approach: Using Foundations and Adapters_. Please follow the instructions [here](../../docs/integrating-into-frameworks.md).

### `MDCTopAppBarAdapter`

Method Signature | Description
--- | ---
`addClass(className: string) => void` | Adds a class to the root element of the component.
`removeClass(className: string) => void` | Removes a class from the root element of the component.
`hasClass(className: string) => boolean` | Checks if the root element of the component has the given className.
`setStyle(property: string, value: string) => void` | Sets the specified CSS property to the given value on the root element.
`getTopAppBarHeight() => number` | Gets the height in px of the top app bar.
`getViewportScrollY() => number` | Gets the number of pixels that the content of body is scrolled from the top of the page.
`getTotalActionItems() => number` | Gets the number of action items in the top app bar.
`notifyNavigationIconClicked() => void` | Emits a custom event `MDCTopAppBar:nav` when the navigation icon is clicked.

### Foundations

#### `MDCTopAppBarBaseFoundation`, `MDCTopAppBarFoundation`, `MDCFixedTopAppBarFoundation` and `MDCShortTopAppBarFoundation`

All foundations provide the following methods:

Method Signature | Description
--- | ---
`handleTargetScroll() => void` | Handles `scroll` event on specified scrollTarget (defaults to `window`).
`handleWindowResize() => void` | Handles `resize` event on window.
`handleNavigationClick() => void` | Handles `click` event on navigation icon.

#### `MDCShortTopAppBarFoundation`

In addition to the methods above, the short variant provides the following public methods and properties:

Method Signature | Description
--- | ---
`setAlwaysCollapsed(value: boolean) => void` | When `value` is `true`, sets the short top app bar to always be collapsed.
`getAlwaysCollapsed() => boolean` | Gets if the short top app bar is in the "always collapsed" state.

Property | Value Type | Description
--- | --- | ---
`isCollapsed` | `boolean` (read-only) | Indicates whether the short top app bar is in the collapsed state.