diff --git a/documentation/docs/02-runes/05-$props.md b/documentation/docs/02-runes/04-$props.md similarity index 100% rename from documentation/docs/02-runes/05-$props.md rename to documentation/docs/02-runes/04-$props.md diff --git a/documentation/docs/02-runes/04-$effect.md b/documentation/docs/02-runes/05-$effect.md similarity index 85% rename from documentation/docs/02-runes/04-$effect.md rename to documentation/docs/02-runes/05-$effect.md index 1ea960de70..0b4fae8320 100644 --- a/documentation/docs/02-runes/04-$effect.md +++ b/documentation/docs/02-runes/05-$effect.md @@ -2,15 +2,11 @@ title: $effect --- -Effects are what make your application _do things_. When Svelte runs an effect function, it tracks which pieces of state (and derived state) are accessed (unless accessed inside [`untrack`](svelte#untrack)), and re-runs the function when that state later changes. +Effects are used for making your application perform _actions_. You might use it to do things like call a third-party library, draw on a `` element, or make a network request. It's important to distinguish these actions from updating state, which should not be done inside an effect. -Most of the effects in a Svelte app are created by Svelte itself — they're the bits that update the text in `

hello {name}!

` when `name` changes, for example. +> [!NOTE] Your application will become a nightmare to deal with almost immediately if you try to update state inside an effect. If you're tempted to use an effect to update state, see [when not to use `$effect`](#When-not-to-use-$effect) to learn about alternative approaches. -But you can also create your own effects with the `$effect` rune, which is useful when you need to synchronize an external system (whether that's a library, or a `` element, or something across a network) with state inside your Svelte app. - -> [!NOTE] Avoid overusing `$effect`! When you do too much work in effects, code often becomes difficult to understand and maintain. See [when not to use `$effect`](#When-not-to-use-$effect) to learn about alternative approaches. - -Your effects run after the component has been mounted to the DOM, and in a [microtask](https://developer.mozilla.org/en-US/docs/Web/API/HTML_DOM_API/Microtask_guide) after state changes ([demo](/playground/untitled#H4sIAAAAAAAAE31S246bMBD9lZF3pSRSAqTVvrCAVPUP2sdSKY4ZwJJjkD0hSVH-vbINuWxXfQH5zMyZc2ZmZLVUaFn6a2R06ZGlHmBrpvnBvb71fWQHVOSwPbf4GS46TajJspRlVhjZU1HqkhQSWPkHIYdXS5xw-Zas3ueI6FRn7qHFS11_xSRZhIxbFtcDtw7SJb1iXaOg5XIFeQGjzyPRaevYNOGZIJ8qogbpe8CWiy_VzEpTXiQUcvPDkSVrSNZz1UlW1N5eLcqmpdXUvaQ4BmqlhZNUCgxuzFHDqUWNAxrYeUM76AzsnOsdiJbrBp_71lKpn3RRbii-4P3f-IMsRxS-wcDV_bL4PmSdBa2wl7pKnbp8DMgVvJm8ZNskKRkEM_OzyOKQFkgqOYBQ3Nq89Ns0nbIl81vMFN-jKoLMTOr-SOBOJS-Z8f5Y6D1wdcR8dFqvEBdetK-PHwj-z-cH8oHPY54wRJ8Ys7iSQ3Bg3VA9azQbmC9k35kKzYa6PoVtfwbbKVnBixBiGn7Pq0rqJoUtHiCZwAM3jdTPWCVtr_glhVrhecIa3vuksJ_b7TqFs4DPyriSjd5IwoNNQaAmNI-ESfR2p8zimzvN1swdCkvJHPH6-_oX8o1SgcIDAAA=)): +You can create an effect with the `$effect` rune ([demo](/playground/untitled#H4sIAAAAAAAAE31S246bMBD9lZF3pSRSAqTVvrCAVPUP2sdSKY4ZwJJjkD0hSVH-vbINuWxXfQH5zMyZc2ZmZLVUaFn6a2R06ZGlHmBrpvnBvb71fWQHVOSwPbf4GS46TajJspRlVhjZU1HqkhQSWPkHIYdXS5xw-Zas3ueI6FRn7qHFS11_xSRZhIxbFtcDtw7SJb1iXaOg5XIFeQGjzyPRaevYNOGZIJ8qogbpe8CWiy_VzEpTXiQUcvPDkSVrSNZz1UlW1N5eLcqmpdXUvaQ4BmqlhZNUCgxuzFHDqUWNAxrYeUM76AzsnOsdiJbrBp_71lKpn3RRbii-4P3f-IMsRxS-wcDV_bL4PmSdBa2wl7pKnbp8DMgVvJm8ZNskKRkEM_OzyOKQFkgqOYBQ3Nq89Ns0nbIl81vMFN-jKoLMTOr-SOBOJS-Z8f5Y6D1wdcR8dFqvEBdetK-PHwj-z-cH8oHPY54wRJ8Ys7iSQ3Bg3VA9azQbmC9k35kKzYa6PoVtfwbbKVnBixBiGn7Pq0rqJoUtHiCZwAM3jdTPWCVtr_glhVrhecIa3vuksJ_b7TqFs4DPyriSjd5IwoNNQaAmNI-ESfR2p8zimzvN1swdCkvJHPH6-_oX8o1SgcIDAAA=)): ```svelte