---
title: "hasChanged"
description: "This function returns true if the given value has changed since the last time the Expression Item was run."
---

# hasChanged

> This function returns true if the given value has changed since the last time the Expression Item was run.

**This function is used by Ignition's Expression language.**

## Description

:::note
This function is only available in [Transaction Group Expression Items](ignition-modules\sql-bridge-transaction-groups\item-types\item-types.md) and [Expression Tags](platform/tags/types-of-tags/types-of-tags.md#expression-tags).
:::

This function returns true if the given value has changed since the last time the Expression Item was run. Setting the optional boolean argument `includeQuality` to true means a quality change will make this function return true.

## Syntax

`hasChanged(value, [includeQuality], [pollRate])`

### Parameters

| Type    | Parameter       | Description                                                                                                   |
|---------|-----------------|---------------------------------------------------------------------------------------------------------------|
| Object  | `value`         | The value to check for changes.                                                                               |
| Boolean | `includeQuality`| A flag that indicates if a quality change will also trigger this function. [optional]                        |
| Integer | `pollRate`      | The poll rate in milliseconds. Only applicable on Expression Tags when the Execution Mode is set to Event Driven. [optional] |

### Returns

**Boolean** - Returns true if the value has changed since the last evaluation, or false otherwise.

## Examples

```python title="Code Snippet"
//Would return true if the referenced Tag has changed in value or quality since the last group execution.

hasChanged({[default]Station 1/Status},True) 
```