feat(transformer): implement key extraction for react automatic (#1077)

crates/oxc_ast/src/ast/jsx.rs

@@ -157,6 +157,12 @@ pub struct JSXAttribute<'a> {
     pub value: Option<JSXAttributeValue<'a>>,
 }
 
+impl<'a> JSXAttribute<'a> {
+    pub fn is_key(&self) -> bool {
+        matches!(&self.name, JSXAttributeName::Identifier(ident) if ident.name == "key")
+    }
+}
+
 /// JSX Spread Attribute
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]

crates/oxc_transformer/src/react_jsx/mod.rs

@@ -53,14 +53,8 @@ impl<'a, 'b> JSXElementOrFragment<'a, 'b> {
         for attr in &e.opening_element.attributes {
             if matches!(attr, JSXAttributeItem::SpreadAttribute(_)) {
                 spread = true;
-            } else if spread {
-                if let JSXAttributeItem::Attribute(a) = attr {
-                    if let JSXAttributeName::Identifier(ident) = &a.name {
-                        if ident.name == "key" {
-                            return true;
-                        }
-                    }
-                }
+            } else if spread && matches!(attr, JSXAttributeItem::Attribute(a) if a.is_key()) {
+                return true;
             }
         }
         false
@@ -165,6 +159,8 @@ impl<'a> ReactJsx<'a> {
     }
 
     fn transform_jsx<'b>(&mut self, e: &JSXElementOrFragment<'a, 'b>) -> Option<Expression<'a>> {
+        let is_classic = self.options.runtime.is_classic();
+        let is_automatic = self.options.runtime.is_automatic();
         let has_key_after_props_spread = e.has_key_after_props_spread();
         let callee = self.get_create_element(has_key_after_props_spread);
         let children = e.children();
@@ -179,6 +175,7 @@ impl<'a> ReactJsx<'a> {
             JSXElementOrFragment::Fragment(_) => self.get_fragment(),
         }));
 
+        let mut key = None;
         // TODO: compute the correct capacity for both runtimes
         let mut properties = self.ast.new_vec_with_capacity(0);
         if let Some(attributes) = e.attributes() {
@@ -186,34 +183,12 @@ impl<'a> ReactJsx<'a> {
                 let kind = PropertyKind::Init;
                 match attribute {
                     JSXAttributeItem::Attribute(attr) => {
+                        if is_automatic && attr.is_key() && !has_key_after_props_spread {
+                            key = attr.value.as_ref();
+                            continue;
+                        }
                         let key = self.get_attribute_name(&attr.name);
-                        let value = match &attr.value {
-                            Some(value) => {
-                                match value {
-                                    JSXAttributeValue::StringLiteral(s) => {
-                                        self.ast.literal_string_expression(s.clone())
-                                    }
-                                    JSXAttributeValue::Element(_)
-                                    | JSXAttributeValue::Fragment(_) => {
-                                        /* TODO */
-                                        continue;
-                                    }
-                                    JSXAttributeValue::ExpressionContainer(c) => {
-                                        match &c.expression {
-                                            JSXExpression::Expression(e) => self.ast.copy(e),
-                                            JSXExpression::EmptyExpression(_e) =>
-                                            /* TODO */
-                                            {
-                                                continue;
-                                            }
-                                        }
-                                    }
-                                }
-                            }
-                            None => {
-                                self.ast.literal_boolean_expression(BooleanLiteral::new(SPAN, true))
-                            }
-                        };
+                        let value = self.transform_jsx_attribute_value(attr.value.as_ref())?;
                         let object_property = self
                             .ast
                             .object_property(SPAN, kind, key, value, None, false, false, false);
@@ -236,12 +211,12 @@ impl<'a> ReactJsx<'a> {
                     },
                 }
             }
-        } else if self.options.runtime.is_classic() {
+        } else if is_classic {
             let null_expr = self.ast.literal_null_expression(NullLiteral::new(SPAN));
             arguments.push(Argument::Expression(null_expr));
         }
 
-        if self.options.runtime.is_automatic() && !children.is_empty() {
+        if is_automatic && !children.is_empty() {
             let key =
                 self.ast.property_key_identifier(IdentifierName::new(SPAN, "children".into()));
             let value = if children.len() == 1 {
@@ -268,12 +243,16 @@ impl<'a> ReactJsx<'a> {
             properties.push(ObjectPropertyKind::ObjectProperty(object_property));
         }
 
-        if !properties.is_empty() || self.options.runtime.is_automatic() {
+        if !properties.is_empty() || is_automatic {
             let object_expression = self.ast.object_expression(SPAN, properties, None);
             arguments.push(Argument::Expression(object_expression));
         }
 
-        if self.options.runtime.is_classic() && !children.is_empty() {
+        if is_automatic && key.is_some() {
+            arguments.push(Argument::Expression(self.transform_jsx_attribute_value(key)?));
+        }
+
+        if is_classic && !children.is_empty() {
             arguments.extend(
                 children
                     .iter()
@@ -373,6 +352,32 @@ impl<'a> ReactJsx<'a> {
         }
     }
 
+    fn transform_jsx_attribute_value(
+        &self,
+        value: Option<&JSXAttributeValue<'a>>,
+    ) -> Option<Expression<'a>> {
+        match value {
+            Some(JSXAttributeValue::StringLiteral(s)) => {
+                Some(self.ast.literal_string_expression(s.clone()))
+            }
+            Some(JSXAttributeValue::Element(_) | JSXAttributeValue::Fragment(_)) => {
+                /* TODO */
+                None
+            }
+            Some(JSXAttributeValue::ExpressionContainer(c)) => {
+                match &c.expression {
+                    JSXExpression::Expression(e) => Some(self.ast.copy(e)),
+                    JSXExpression::EmptyExpression(_e) =>
+                    /* TODO */
+                    {
+                        None
+                    }
+                }
+            }
+            None => Some(self.ast.literal_boolean_expression(BooleanLiteral::new(SPAN, true))),
+        }
+    }
+
     fn transform_jsx_member_expression(&self, expr: &JSXMemberExpression<'a>) -> Expression<'a> {
         let object = match &expr.object {
             JSXMemberExpressionObject::Identifier(ident) => {

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 214/1083
+Passed: 215/1083
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
@@ -804,7 +804,7 @@ Passed: 214/1083
 * regression/11061/input.mjs
 * variable-declaration/non-null-in-optional-chain/input.ts
 
-# babel-plugin-transform-react-jsx (65/172)
+# babel-plugin-transform-react-jsx (66/172)
 * autoImport/after-polyfills/input.mjs
 * autoImport/after-polyfills-2/input.mjs
 * autoImport/after-polyfills-compiled-to-cjs/input.mjs
@@ -895,7 +895,6 @@ Passed: 214/1083
 * react-automatic/should-properly-handle-keys/input.js
 * react-automatic/should-support-xml-namespaces-if-flag/input.js
 * react-automatic/should-throw-when-filter-is-specified/input.js
-* react-automatic/should-use-jsx-when-key-comes-before-spread/input.js
 * react-automatic/should-warn-when-pragma-or-pragmaFrag-is-set/input.js
 * react-automatic/weird-symbols/input.js
 * regression/issue-12478-automatic/input.js