From d6abd0a6040a5ef2f2291c60498a5c6653476ea1 Mon Sep 17 00:00:00 2001 From: Ben McCann <322311+benmccann@users.noreply.github.com> Date: Thu, 27 Jul 2023 11:50:46 -0700 Subject: [PATCH] docs: clarify performance concerns around props and restProps (#9047) * docs: clarify performance concerns around props and restProps * Update documentation/docs/02-template-syntax/02-basic-markup.md --- documentation/docs/02-template-syntax/02-basic-markup.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/documentation/docs/02-template-syntax/02-basic-markup.md b/documentation/docs/02-template-syntax/02-basic-markup.md index 281790ac71..9e230078b5 100644 --- a/documentation/docs/02-template-syntax/02-basic-markup.md +++ b/documentation/docs/02-template-syntax/02-basic-markup.md @@ -85,13 +85,13 @@ An element or component can have multiple spread attributes, interspersed with r ``` -`$$props` references all props that are passed to a component, including ones that are not declared with `export`. It is not generally recommended, as it is difficult for Svelte to optimise. But it can be useful in rare cases – for example, when you don't know at compile time what props might be passed to a component. +`$$props` references all props that are passed to a component, including ones that are not declared with `export`. Using `$$props` will not perform as well as references to a specific prop because changes to any prop will cause Svelte to recheck all usages of `$$props`. But it can be useful in some cases – for example, when you don't know at compile time what props might be passed to a component. ```svelte ``` -`$$restProps` contains only the props which are _not_ declared with `export`. It can be used to pass down other unknown attributes to an element in a component. It shares the same optimisation problems as `$$props`, and is likewise not recommended. +`$$restProps` contains only the props which are _not_ declared with `export`. It can be used to pass down other unknown attributes to an element in a component. It shares the same performance characteristics compared to specific property access as `$$props`. ```svelte