> For the complete documentation index, see [llms.txt](https://docs.feathery.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.feathery.io/platform/build-forms/advanced-logic/examples/update-field-options-based-on-previous-selection.md).

# Update field options based on previous selection

Update the options of a dropdown field based on what the user selects in the previous dropdown field.

## Overview

In this example, the options in Dropdown B will be updated dynamically based on what the user selects as the value for Dropdown A. Dropdown A's options will be `Positive` and `Negative`, and Dropdown B will display positive or negative number options accordingly.

## Rule Logic

This rule should run when the value of Dropdown A is changed and when the step that Dropdown B is on is loaded.

```
if (DropdownA.value === 'Positive') DropdownB.options = ['1', '2', '3'];
else DropdownB.options = ['-1', '-2', '-3'];
```


---

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