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Zenon Page Templates - JS (ZPT-JS)
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<h1>ZPT-JS reference - Attributes - TALCondition</h1>
<ul>
<li><a href="#syntax">Syntax</a>.</li>
<li><a href="#description">Description</a>.</li>
<li><a href="#differences">Differences with ZPT</a>.</li>
<li><a href="#examples">Examples</a>.</li>
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<h2 data-attributes="id 'syntax'">Syntax</h2>
<pre class="syntax">
argument ::= expression
</pre>
<h2 data-attributes="id 'description'">Description</h2>
<p>
The <em>data-condition</em> statement includes the statement element in the template only if the condition is met, and omits it otherwise. If its expression evaluates to a <code>true</code> value, then normal processing of the element continues, otherwise the statement element is immediately removed from the template.
</p>
<p>
If an expression evaluates to any of the next:
</p>
<ul>
<li><code>undefined</code></li>
<li><code>null</code></li>
<li><code>'false'</code></li>
<li><code>false</code></li>
<li><code>0</code></li>
</ul>
<p>
the expression evaluates to <code>false</code>. Otherwise the expression evaluates to <code>true</code>.
</p>
<p>
Note: extracted from <a href="https://zope.readthedocs.io/en/latest/zopebook/AppendixC.html#condition-conditionally-insert-or-remove-an-element">Zope Page Templates Reference</a>.
</p>
<h2 data-attributes="id 'differences'">Differences with ZPT</h2>
<p>
None.
</p>
<h2 data-attributes="id 'examples'">Examples</h2>
<p>
Test a variable before inserting it (the first example tests for existence and truth, while the second only tests for existence):
</p>
<pre class="brush: html">
<p datat-condition="myObject/message"
data-content="myObject/message">
Message goes here
</p>
<p datat-condition="exists: myObject/message"
data-content="myObject/message">
Message goes here
</p>
</pre>
<p>
Test for alternate conditions:
</p>
<pre class="brush: html">
<div data-repeat="item [1:10]">
<span data-replace="item-repeat/index()">1</span>
is
<span data-condition="item-repeat/even()">even</span>
<span data-condition="item-repeat/odd()">odd</span>
</div>
</pre>
<p>
Test for alternate conditions in action:
</p>
<div data-repeat="item [1:10]">
<span data-replace="item-repeat/index()">1</span>
is
<span data-condition="item-repeat/even()">even</span>
<span data-condition="item-repeat/odd()">odd</span>
</div>
<p>
Note: extracted from <a href="https://zope.readthedocs.io/en/latest/zopebook/AppendixC.html#condition-conditionally-insert-or-remove-an-element">Zope Page Templates Reference</a>.
</p>
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