# Adding watch expressions [edit]

This page describes how to add watch expressions to help inspect your scripts in Firebug.

## Introduction

Use watch expressions to determine the value of an expression or object in your code. This can help you determine if the type and value of the expression are what you were expecting them to be.

## Instructions

To add a watch expression to your code:

1. In the lower right corner of Firefox, click the Firebug button to start Firebug.
2. Click the tab to view the Script tab.
3. Click the tab.
4. Click the yellow New Watch Expression... field to enable the field, then type your watch expression, and press the Enter key. (e.g. "document").

   Firebug displays the value for your watch expression, which you can expand and collapse as needed.

## Related Topics

- About Firebug
- Installing the Firebug extension
- Inspecting HTML
- Inspecting CSS
- Stepping through your code
- Monitoring XMLHttpRequests
- Editing a web page
- Writing to the Firebug console
- Setting breakpoints in Firebug
- Profiling code performance

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Category: AptanaHelp