using-conditional-templates.html

<!--
Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->

<!--
# Using Conditional Templates

Shows the use of a conditional template using **if=** syntax:

    <template if="{{showAnswer}}">
      ...
    </template>

The template renders only if the value it is bound to is truthy.

Polymer has no `else` clause. Use a negative condition instead:

    <template if="{{!showAnswer}}">
      ...
    </template>

Read the
[official documentation for conditional templates](http://www.polymer-project.org/docs/polymer/binding-types.html#conditional-templates).

[jsbin](http://jsbin.com/wigala/edit)
-->

<link rel="import" href="../../components/polymer/polymer.html">

<polymer-element name="my-element">
  <template>
    <template if="{{showAnswer}}">
      <div>42</div>
      <button on-tap="{{toggleView}}">Show question</button>
    </template>
    <template if="{{!showAnswer}}">
      <div>
        What is the answer to "The Ultimate Question of Life, the
        Universe, and Everything"?
      </div>
      <button on-tap="{{toggleView}}">Show answer</button>
    </template>
  </template>
  <script>
    Polymer({
      showAnswer: false,
      toggleView: function(e, detail, sender) {
        this.showAnswer = !this.showAnswer;
      }
    });
  </script>
</polymer-element>