In templates it is possible to use the if blocks to control the output depending on the data. The if block is opened with the expression {{#if condition} and closed with {{/ if}}. Optionally, it is possible to use an else branch. The following values are considered false: false, undefined, null, "", 0 and [].
Template:
<div>
{{#if author}}
<h1>{{author.firstName}} {{author.lastName}}</h1>
{{else}}
<h1>Unknown Author</h1>
{{/if}}
</div>
Data:
{
author: {
firstName: 'John',
lastName: 'Doe'
}
}
Result:
<div>
<h1>John Doe</h1>
</div>
