docs: Update Breaking changes section (#9444)

* update docs * Update sites/svelte-5-preview/src/routes/docs/content/03-appendix/02-breaking-changes.md Co-authored-by: Ben McCann <[email protected]> * Update sites/svelte-5-preview/src/routes/docs/content/03-appendix/02-breaking-changes.md * Update sites/svelte-5-preview/src/routes/docs/content/03-appendix/02-breaking-changes.md --------- Co-authored-by: Simon H <[email protected]> Co-authored-by: Ben McCann <[email protected]> Co-authored-by: Rich Harris <[email protected]>
sveltejs · Nov 14, 2023 · f18adc8 · f18adc8 · vercel · Nov 14, 2023
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diff --git a/sites/svelte-5-preview/src/routes/docs/content/03-appendix/02-breaking-changes.md b/sites/svelte-5-preview/src/routes/docs/content/03-appendix/02-breaking-changes.md
@@ -75,3 +75,13 @@ Previously Svelte would always insert the CSS hash last. This is no longer guara
 ### `contenteditable` behavior change
 
 If you have a `contenteditable` node with a corresponding binding _and_ a reactive value inside it (example: `<div contenteditable=true bind:textContent>count is {count}</div>`), then the value inside the contenteditable will not be updated by updates to `count` because the binding takes full control over the content immediately and it should only be updated through it.
+
+### `oneventname` attributes no longer accept string values
+
+In Svelte 4, it was possible to specify event attributes on HTML elements as a string:
+
+```svelte
+<button onclick="alert('hello')">...</button>
+```
+
+This is not recommended, and is no longer possible in Svelte 5, where properties like `onclick` replace `on:click` as the mechanism for adding [event handlers](/docs/event-handlers).