3 files changed, 17 insertions, 6 deletions
diff --git a/packages/astro/src/ast.ts b/packages/astro/src/ast.ts
index f80084cb2..bee1d9b6f 100644
--- a/packages/astro/src/ast.ts
+++ b/packages/astro/src/ast.ts
@@ -11,6 +11,7 @@ export function getAttr(attributes: Attribute[], name: string): Attribute | unde
 
 /** Get TemplateNode attribute by value */
 export function getAttrValue(attributes: Attribute[], name: string): string | undefined {
+  if (attributes.length === 0) return '';
   const attr = getAttr(attributes, name);
   if (attr) {
     return attr.value[0]?.data;
diff --git a/packages/astro/src/compiler/codegen/index.ts b/packages/astro/src/compiler/codegen/index.ts
index 97687b4a9..9271ab50a 100644
--- a/packages/astro/src/compiler/codegen/index.ts
+++ b/packages/astro/src/compiler/codegen/index.ts
@@ -58,6 +58,10 @@ function getAttributes(attrs: Attribute[]): Record<string, string> {
       // note: attr.value shouldn’t be `undefined`, but a bad transform would cause a compile error here, so prevent that
       continue;
     }
+    if (attr.value.length === 0) {
+      result[attr.name] = '""';
+      continue;
+    }
     if (attr.value.length > 1) {
       result[attr.name] =
         '(' +
@@ -418,6 +422,8 @@ function dedent(str: string) {
   return !arr || !first ? str : str.replace(new RegExp(`^[ \\t]{0,${first}}`, 'gm'), '');
 }
 
+const FALSY_EXPRESSIONS = new Set(['false','null','undefined','void 0']);
+
 /** Compile page markup */
 async function compileHtml(enterNode: TemplateNode, state: CodegenState, compileOptions: CompileOptions): Promise<string> {
   return new Promise((resolve) => {
@@ -475,10 +481,12 @@ async function compileHtml(enterNode: TemplateNode, state: CodegenState, compile
             }
             // TODO Do we need to compile this now, or should we compile the entire module at the end?
             let code = compileExpressionSafe(raw).trim().replace(/\;$/, '');
-            if (state.markers.insideMarkdown) {
-              buffers[curr] += `{${code}}`;
-            } else {
-              buffers[curr] += `,(${code})`;
+            if (!FALSY_EXPRESSIONS.has(code)) {
+              if (state.markers.insideMarkdown) {
+                buffers[curr] += `{${code}}`;
+              } else {
+                buffers[curr] += `,(${code})`;
+              }
             }
             this.skip();
             break;
diff --git a/packages/astro/src/frontend/h.ts b/packages/astro/src/frontend/h.ts
index ae54072a8..bcfb4833f 100644
--- a/packages/astro/src/frontend/h.ts
+++ b/packages/astro/src/frontend/h.ts
@@ -19,7 +19,9 @@ function* _h(tag: string, attrs: HProps, children: Array<HChild>) {
   yield `<${tag}`;
   if (attrs) {
     for (let [key, value] of Object.entries(attrs)) {
-      yield ` ${key}="${value}"`;
+      if (value === '') yield ` ${key}=""`;
+      else if (value == null) yield '';
+      else yield ` ${key}="${value}"`;
     }
   }
   yield '>';
@@ -37,7 +39,7 @@ function* _h(tag: string, attrs: HProps, children: Array<HChild>) {
       yield child();
     } else if (typeof child === 'string') {
       yield child;
-    } else if (!child) {
+    } else if (!child && child !== 0) {
       // do nothing, safe to ignore falsey values.
     } else {
       yield child;