---
title: "Watchers · vuejs.school"
description: "Run a side effect when state changes with watch() and watchEffect(), and know when a computed is the better tool."
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> Index of every page on this site: [llms.txt](https://vuejs.school/llms.txt)

# **Watchers**

Run a side effect when state changes with watch() and watchEffect(), and know when a computed is the better tool.

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