# is\_undefined

Source: https://zotonic.com/docs/1848/is_undefined

URI: https://zotonic.com/id/1848

Language: en



Tests if a value is undefined.

Checks if the value is empty and outputs a boolean true or false. This is useful in combination with the <a href="/id/doc_template_tag_tag_if" class="doc-reference doc-reference-tag"><code>tag#if</code></a> tag.

For example:

```django
{% if value[1]|is_undefined %}The first elemeent of value was undefined{% endif %}
```

If the value is `[]` then the output is `The first elemeent of value was undefined`.

License: 

Attribution: 

Related resources: https://zotonic.com/api/agent/related/1848?language=en


## API access

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- [This resource as JSON](<https://zotonic.com/api/agent/resource/1848?language=en>)