---
title: "__isPropDefined"
description: "JMeter __isPropDefined function reference: syntax, parameters, and practical examples for parameterizing test plans with dynamic values."
url: https://docs.jmeter.ai/functions/ispropdefined/
lastUpdated: 2026-10-01
source: docs.jmeter.ai
---

# __isPropDefined

*Also documented in context in the [full Functions and Variables reference](/user-manual/functions/#__isPropDefined).*

The `__isPropDefined` function returns true if property exists or false if not.

| Name | Required | Description |
| --- | --- | --- |
| Property Name | Yes | The Property Name to be used to check if defined |

Example:

```bash
\${__isPropDefined(START.HMS)}
```

will return `true`

## Related

- [Functions and Variables Guide](/topics/functions-and-variables/)
- [Regex Extractor Builder](/tools/regex-tester/)
- [Full Functions Reference](/user-manual/functions/)
- [Component Reference](/user-manual/component-reference/)