Merge 6614dca136 into ce89035ecb

.changeset/heavy-pandas-shout.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: serialize `<textarea>` default values during server rendering

packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/element.js

@@ -88,6 +88,13 @@ export function build_element_attributes(node, context, transform) {
 				attributes.push(attribute);
 				// deopt to spread at runtime, where we can handle interaction of value/defaultValue etc
 				has_spread = true;
+			} else if (
+				node.type === 'RegularElement' &&
+				node.name === 'textarea' &&
+				attribute.name === 'defaultValue' &&
+				renders_default_value_as_content(node)
+			) {
+				content = b.call('$.escape', build_attribute_value(attribute.value, context, transform));
 				// the defaultValue/defaultChecked properties don't exist as attributes
 			} else if (attribute.name !== 'defaultValue' && attribute.name !== 'defaultChecked') {
 				if (attribute.name === 'class') {
@@ -293,6 +300,23 @@ export function build_element_attributes(node, context, transform) {
 	return content;
 }
 
+/**
+ * A `<textarea>` has no value attribute, so `defaultValue` can only be serialized as its content,
+ * which is possible when nothing else already provides one.
+ * @param {AST.RegularElement} node
+ */
+function renders_default_value_as_content(node) {
+	return (
+		node.fragment.nodes.length === 0 &&
+		!node.attributes.some(
+			(attribute) =>
+				attribute.type === 'SpreadAttribute' ||
+				((attribute.type === 'Attribute' || attribute.type === 'BindDirective') &&
+					attribute.name === 'value')
+		)
+	);
+}
+
 /**
  * @param {AST.RegularElement | AST.SvelteElement} element
  * @param {AST.Attribute | AST.BindDirective} attribute

packages/svelte/tests/server-side-rendering/samples/textarea-default-value/_config.js

@@ -0,0 +1,3 @@
+import { test } from '../../test';
+
+export default test({});

packages/svelte/tests/server-side-rendering/samples/textarea-default-value/_expected.html

@@ -0,0 +1,4 @@
+<textarea>hello</textarea>
+<textarea>world</textarea>
+<textarea>content wins</textarea>
+<textarea>value wins</textarea>

packages/svelte/tests/server-side-rendering/samples/textarea-default-value/main.svelte

@@ -0,0 +1,8 @@
+<script>
+	let dynamic = 'world';
+</script>
+
+<textarea defaultValue="hello"></textarea>
+<textarea defaultValue={dynamic}></textarea>
+<textarea defaultValue="hello">content wins</textarea>
+<textarea defaultValue="hello" value="value wins"></textarea>