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@manucorporat manucorporat released this 31 Oct 19:26
v4.0.0-beta.15-0
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manucorporat Manu MA
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Learn about vigilant mode.

Rethinking Tabs

One of the most valuable and complex components in Ionic's toolkit is Tabs. Tabs started off as a simple component that would create a tabbed interface to allow users to switch between different views in a way that was consistent with native UX paradigms.

Over time, we started hearing people ask for more features to be added: "Can we have one tab button that is just a button?" "Can I customize how the tab buttons are displayed?" "Can I use a custom icon in the tab?"

Traditionally, these features, and many others, were difficult to accomplish because Tabs was doing a lot of magic behind the scenes to generate the Tab bar and buttons. With this in mind, we thought it was time for a refresh to offer as much flexibility as possible within Tabs.

In order to do this, we had to change how Tabs were written in an app. Prior to Beta 14, Tabs would look like this:

<ion-tabs>
  <ion-tab label="Home" icon="home" href="/tabs/(home:home)">
    <ion-router-outlet name="home"></ion-router-outlet>
  </ion-tab>
  <ion-tab label="About" icon="information-circle" href="/tabs/(about:about)">
    <ion-router-outlet name="about"></ion-router-outlet>
  </ion-tab>
  <ion-tab label="Contact" icon="contacts" href="/tabs/(contact:contact)">
    <ion-router-outlet name="contact"></ion-router-outlet>
  </ion-tab>
</ion-tabs>

Here, we have an ion-tab element that accepts an icon, a label, and a link to navigate to as properties. This is pretty much how Tabs have worked all the way back to Ionic 1. In Beta 14, we've removed some of the magic from Tabs which allows for more customization:

<ion-tabs>
  <ion-tab-bar>

    <!-- No ion-tab, just a link that looks like a tab -->
    <ion-tab-button href=”https://beta.ionicframework.com”>
      <!-- <a href=”https://beta.ionicframework.com”> -->
      <ion-icon name="globe"></ion-icon>
      <ion-label>Schedule</ion-label>
    </ion-tab-button>

    <!-- No ion-tab, just a button that looks like a tab -->
    <ion-tab-button (click)=”openCamera()”>
      <ion-icon name="camera"></ion-icon>
      <ion-label>Photo</ion-label>
    </ion-tab-button>

    <!-- Connected to ion-tab, on click will show the ion-tab with id home-view -->
    <ion-tab-button tab=”home-view”>
      <ion-icon name="home"></ion-icon>
      <ion-label>Home</ion-label>
    </ion-tab-button>
  </ion-tab-bar>

  <ion-tab tab=”home-view”>
    <ion-content></ion-content>
    <!-- or -->
    <ion-nav></ion-nav>
    <!-- or -->
    <ion-router-outlet></ion-router-outlet>
  </ion-tab>

</ion-tabs>

There's a lot going on here, so let's break it down:

  1. A single parent ion-tabs wraps the entire layout. Same as before.
  2. A new element, ion-tab-bar, creates the Tab Bar which will contain buttons.
  3. A new element, ion-tab-button, is used to create each button in the Tab Bar. These could be static links to different routes, buttons with click handlers on them, or link to whole tab views.
  4. The ion-tab component becomes a separate container that has inline content (ion-content), a navigation component (ion-nav) or a router outlet (ion-router-outlet).

To connect the ion-tab-button to the ion-tab, the tab property must be added to both of these components. For example:

<ion-tabs>
  <ion-tab-bar>
    <ion-tab-button tab=”home-view”></ion-tab-button>
  </ion-tab-bar>

  <ion-tab tab=”home-view”></ion-tab>
</ion-tabs>

Since the tab property is the same on the ion-tab-button and ion-tab, when the Tab Button is tapped, the home-view Tab will become active. This takes the magic out of Tabs while making the behavior between the tab buttons and the views much more explicit.

Some other benefits of this refactor include:

  • Can now be written as a standalone Tab Bar (with no attached Tab)
  • Works with a navigation component or a plain content element
  • Works with shadow DOM and allows easy customization of the Tab Bar
  • Gives full control over the elements inside of the Tab Bar
  • Integrates nicely with other frameworks that have different ways of rendering element nodes

Lastly, this change also fixes some outstanding issues with Tabs, so we're excited to get this out to you all!

Bug Fixes

Features

Performance Improvements

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