SSR

Author: Rich-Harris

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

@@ -44,15 +44,17 @@ export function process_children(nodes, { visit, state }) {
 			if (node.type === 'Text' || node.type === 'Comment') {
 				quasi.value.cooked +=
 					node.type === 'Comment' ? `<!--${node.data}-->` : escape_html(node.data);
-			} else if (node.type === 'ExpressionTag' && node.expression.type === 'Literal') {
-				if (node.expression.value != null) {
-					quasi.value.cooked += escape_html(node.expression.value + '');
-				}
 			} else {
-				expressions.push(b.call('$.escape', /** @type {Expression} */ (visit(node.expression))));
+				const evaluated = state.scope.evaluate(node.expression);
+
+				if (evaluated.is_known) {
+					quasi.value.cooked += escape_html((evaluated.value ?? '') + '');
+				} else {
+					expressions.push(b.call('$.escape', /** @type {Expression} */ (visit(node.expression))));
 
-				quasi = b.quasi('', i + 1 === sequence.length);
-				quasis.push(quasi);
+					quasi = b.quasi('', i + 1 === sequence.length);
+					quasis.push(quasi);
+				}
 			}
 		}
 

packages/svelte/src/compiler/phases/scope.js

@@ -113,7 +113,7 @@ class Evaluation {
 	 * @readonly
 	 * @type {boolean}
 	 */
-	is_known = false;
+	is_known = true;
 
 	/**
 	 * True if the value is known to not be null/undefined
@@ -165,7 +165,12 @@ class Evaluation {
 						break;
 					}
 
-					if (!binding.updated && binding.initial !== null) {
+					const is_prop =
+						binding.kind === 'prop' ||
+						binding.kind === 'rest_prop' ||
+						binding.kind === 'bindable_prop';
+
+					if (!binding.updated && binding.initial !== null && !is_prop) {
 						const evaluation = binding.scope.evaluate(/** @type {Expression} */ (binding.initial));
 						for (const value of evaluation.values) {
 							this.values.add(value);
@@ -293,7 +298,7 @@ class Evaluation {
 				break;
 
 			case 'UnaryExpression':
-				const argument = scope.evaluate(expression.argument);
+				var argument = scope.evaluate(expression.argument);
 
 				if (argument.is_known) {
 					this.values.add(unary[expression.operator](argument.value));
@@ -326,6 +331,7 @@ class Evaluation {
 						// TypeScript getting confused
 						throw new Error(`Unknown operator ${expression.operator}`);
 				}
+				break;
 
 			default:
 				this.values.add(UNKNOWN);
@@ -347,7 +353,9 @@ class Evaluation {
 			}
 		}
 
-		this.is_known = this.values.size === 1 && typeof this.value !== 'symbol';
+		if (this.values.size > 1 || typeof this.value === 'symbol') {
+			this.is_known = false;
+		}
 	}
 }
 

packages/svelte/tests/snapshot/samples/nullish-coallescence-omittance/_expected/server/index.svelte.js

@@ -4,5 +4,5 @@ export default function Nullish_coallescence_omittance($$payload) {
 	let name = 'world';
 	let count = 0;
 
-	$$payload.out += `<h1>Hello, ${$.escape(name)}!</h1> <b>${$.escape(1 ?? 'stuff')}${$.escape(2 ?? 'more stuff')}${$.escape(3 ?? 'even more stuff')}</b> <button>Count is ${$.escape(count)}</button> <h1>Hello, ${$.escape(name ?? 'earth' ?? null)}</h1>`;
+	$$payload.out += `<h1>Hello, world!</h1> <b>123</b> <button>Count is ${$.escape(count)}</button> <h1>Hello, world</h1>`;
 }

packages/svelte/tests/sourcemaps/samples/attached-sourcemap/input.svelte

@@ -8,4 +8,4 @@
 		replace_me_script = 'hello'
 	;
 </script>
-<h1 class="done_replace_style_2">{done_replace_script_2}</h1>
+<h1 class="done_replace_style_2">{Math.random() < 1 && done_replace_script_2}</h1>