feat(biome_js_parser): support defer attribute in import statements

CHANGELOG.md

@@ -178,6 +178,16 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
 ### Parser
 
+#### New features
+
+- JS Parser support defer attribute in import statements ([#4215](https://github.com/biomejs/biome/issues/4215)).
+
+   ```js
+   import defer * as myModule from "my-module";
+   ```
+
+  Contributed by @fireairforce
+
 #### Bug Fixes
 
 - The CSS parser now accepts more emoji in identifiers ([#3627](https://github.com/biomejs/biome/issues/3627#issuecomment-2392388022)).

crates/biome_js_formatter/src/js/module/import_namespace_clause.rs

@@ -13,13 +13,17 @@ impl FormatNodeRule<JsImportNamespaceClause> for FormatJsImportNamespaceClause {
             type_token,
             namespace_specifier,
             from_token,
+            defer_token,
             source,
             assertion,
         } = node.as_fields();
 
         if let Some(type_token) = type_token {
             write!(f, [type_token.format(), space()])?;
         }
+        if let Some(defer_token) = defer_token {
+            write!(f, [defer_token.format(), space()])?;
+        }
 
         write![
             f,

crates/biome_js_parser/src/lexer/mod.rs

@@ -1034,6 +1034,7 @@ impl<'src> JsLexer<'src> {
             b"of" => OF_KW,
             b"out" => OUT_KW,
             b"using" => USING_KW,
+            b"defer" => DEFER_KW,
             _ => T![ident],
         }
     }

crates/biome_js_parser/src/syntax/module.rs

@@ -294,6 +294,28 @@ fn parse_import_clause(p: &mut JsParser) -> ParsedSyntax {
         p.eat(T![type]);
     }
 
+    // test js import_defer_clause
+    // import defer * as yNamespace from "y";
+    let is_defer = 'is_defer: {
+        if !p.at(T![defer]) {
+            break 'is_defer false;
+        }
+
+        if matches!(p.nth(1), T![*] | T!['{']) {
+            break 'is_defer true;
+        }
+
+        if !is_nth_at_identifier_binding(p, 1) {
+            break 'is_defer false;
+        }
+
+        !p.nth_at(1, T![from]) || p.nth_at(2, T![from])
+    };
+
+    if is_defer {
+        p.eat(T![defer]);
+    }
+
     let clause = match p.cur() {
         T![*] => parse_import_namespace_clause_rest(p, m),
         T!['{'] => parse_import_named_clause_rest(p, m),

crates/biome_js_parser/src/tests.rs

@@ -408,7 +408,7 @@ fn diagnostics_print_correctly() {
 #[test]
 pub fn quick_test() {
     let code = r#"
-        type Equals = A extends (x: B extends C ? D : E) => 0 ? F : G;
+        import defer * as yNamespace from "y";
     "#;
     let root = parse(
         code,

crates/biome_js_parser/test_data/inline/err/import_err.rast

@@ -12,6 +12,7 @@ JsModule {
             import_token: IMPORT_KW@7..15 "import" [Newline("\n")] [Whitespace(" ")],
             import_clause: JsImportNamespaceClause {
                 type_token: missing (optional),
+                defer_token: missing (optional),
                 namespace_specifier: JsNamespaceImportSpecifier {
                     star_token: STAR@15..16 "*" [] [],
                     as_token: missing (required),
@@ -27,6 +28,7 @@ JsModule {
             import_token: IMPORT_KW@17..25 "import" [Newline("\n")] [Whitespace(" ")],
             import_clause: JsImportNamespaceClause {
                 type_token: missing (optional),
+                defer_token: missing (optional),
                 namespace_specifier: JsNamespaceImportSpecifier {
                     star_token: STAR@25..27 "*" [] [Whitespace(" ")],
                     as_token: AS_KW@27..30 "as" [] [Whitespace(" ")],
@@ -291,26 +293,28 @@ JsModule {
       0: IMPORT_KW@7..15 "import" [Newline("\n")] [Whitespace(" ")]
       1: JS_IMPORT_NAMESPACE_CLAUSE@15..16
         0: (empty)
-        1: JS_NAMESPACE_IMPORT_SPECIFIER@15..16
+        1: (empty)
+        2: JS_NAMESPACE_IMPORT_SPECIFIER@15..16
           0: STAR@15..16 "*" [] []
           1: (empty)
           2: (empty)
-        2: (empty)
         3: (empty)
         4: (empty)
+        5: (empty)
       2: SEMICOLON@16..17 ";" [] []
     2: JS_IMPORT@17..31
       0: IMPORT_KW@17..25 "import" [Newline("\n")] [Whitespace(" ")]
       1: JS_IMPORT_NAMESPACE_CLAUSE@25..31
         0: (empty)
-        1: JS_NAMESPACE_IMPORT_SPECIFIER@25..31
+        1: (empty)
+        2: JS_NAMESPACE_IMPORT_SPECIFIER@25..31
           0: STAR@25..27 "*" [] [Whitespace(" ")]
           1: AS_KW@27..30 "as" [] [Whitespace(" ")]
           2: JS_IDENTIFIER_BINDING@30..31
             0: IDENT@30..31 "c" [] []
-        2: (empty)
         3: (empty)
         4: (empty)
+        5: (empty)
       2: (empty)
     3: JS_BOGUS_STATEMENT@31..33
       0: COMMA@31..33 "," [] [Whitespace(" ")]

crates/biome_js_parser/test_data/inline/ok/import_decl.rast

@@ -7,6 +7,7 @@ JsModule {
             import_token: IMPORT_KW@0..7 "import" [] [Whitespace(" ")],
             import_clause: JsImportNamespaceClause {
                 type_token: missing (optional),
+                defer_token: missing (optional),
                 namespace_specifier: JsNamespaceImportSpecifier {
                     star_token: STAR@7..9 "*" [] [Whitespace(" ")],
                     as_token: AS_KW@9..12 "as" [] [Whitespace(" ")],
@@ -35,14 +36,15 @@ JsModule {
       0: IMPORT_KW@0..7 "import" [] [Whitespace(" ")]
       1: JS_IMPORT_NAMESPACE_CLAUSE@7..26
         0: (empty)
-        1: JS_NAMESPACE_IMPORT_SPECIFIER@7..16
+        1: (empty)
+        2: JS_NAMESPACE_IMPORT_SPECIFIER@7..16
           0: STAR@7..9 "*" [] [Whitespace(" ")]
           1: AS_KW@9..12 "as" [] [Whitespace(" ")]
           2: JS_IDENTIFIER_BINDING@12..16
             0: IDENT@12..16 "foo" [] [Whitespace(" ")]
-        2: FROM_KW@16..21 "from" [] [Whitespace(" ")]
-        3: JS_MODULE_SOURCE@21..26
+        3: FROM_KW@16..21 "from" [] [Whitespace(" ")]
+        4: JS_MODULE_SOURCE@21..26
           0: JS_STRING_LITERAL@21..26 "\"bla\"" [] []
-        4: (empty)
+        5: (empty)
       2: SEMICOLON@26..27 ";" [] []
   4: EOF@27..28 "" [Newline("\n")] []

crates/biome_js_parser/test_data/inline/ok/import_defer_clause.js

@@ -0,0 +1 @@
+import defer * as yNamespace from "y";

crates/biome_js_parser/test_data/inline/ok/import_defer_clause.rast

@@ -0,0 +1,50 @@
+JsModule {
+    bom_token: missing (optional),
+    interpreter_token: missing (optional),
+    directives: JsDirectiveList [],
+    items: JsModuleItemList [
+        JsImport {
+            import_token: IMPORT_KW@0..7 "import" [] [Whitespace(" ")],
+            import_clause: JsImportNamespaceClause {
+                type_token: missing (optional),
+                defer_token: DEFER_KW@7..13 "defer" [] [Whitespace(" ")],
+                namespace_specifier: JsNamespaceImportSpecifier {
+                    star_token: STAR@13..15 "*" [] [Whitespace(" ")],
+                    as_token: AS_KW@15..18 "as" [] [Whitespace(" ")],
+                    local_name: JsIdentifierBinding {
+                        name_token: IDENT@18..29 "yNamespace" [] [Whitespace(" ")],
+                    },
+                },
+                from_token: FROM_KW@29..34 "from" [] [Whitespace(" ")],
+                source: JsModuleSource {
+                    value_token: JS_STRING_LITERAL@34..37 "\"y\"" [] [],
+                },
+                assertion: missing (optional),
+            },
+            semicolon_token: SEMICOLON@37..38 ";" [] [],
+        },
+    ],
+    eof_token: EOF@38..39 "" [Newline("\n")] [],
+}
+
+0: JS_MODULE@0..39
+  0: (empty)
+  1: (empty)
+  2: JS_DIRECTIVE_LIST@0..0
+  3: JS_MODULE_ITEM_LIST@0..38
+    0: JS_IMPORT@0..38
+      0: IMPORT_KW@0..7 "import" [] [Whitespace(" ")]
+      1: JS_IMPORT_NAMESPACE_CLAUSE@7..37
+        0: (empty)
+        1: DEFER_KW@7..13 "defer" [] [Whitespace(" ")]
+        2: JS_NAMESPACE_IMPORT_SPECIFIER@13..29
+          0: STAR@13..15 "*" [] [Whitespace(" ")]
+          1: AS_KW@15..18 "as" [] [Whitespace(" ")]
+          2: JS_IDENTIFIER_BINDING@18..29
+            0: IDENT@18..29 "yNamespace" [] [Whitespace(" ")]
+        3: FROM_KW@29..34 "from" [] [Whitespace(" ")]
+        4: JS_MODULE_SOURCE@34..37
+          0: JS_STRING_LITERAL@34..37 "\"y\"" [] []
+        5: (empty)
+      2: SEMICOLON@37..38 ";" [] []
+  4: EOF@38..39 "" [Newline("\n")] []

crates/biome_js_parser/test_data/inline/ok/ts_import_clause_types.rast

@@ -41,6 +41,7 @@ JsModule {
             import_token: IMPORT_KW@69..77 "import" [Newline("\n")] [Whitespace(" ")],
             import_clause: JsImportNamespaceClause {
                 type_token: TYPE_KW@77..82 "type" [] [Whitespace(" ")],
+                defer_token: missing (optional),
                 namespace_specifier: JsNamespaceImportSpecifier {
                     star_token: STAR@82..84 "*" [] [Whitespace(" ")],
                     as_token: AS_KW@84..87 "as" [] [Whitespace(" ")],
@@ -134,15 +135,16 @@ JsModule {
       0: IMPORT_KW@69..77 "import" [Newline("\n")] [Whitespace(" ")]
       1: JS_IMPORT_NAMESPACE_CLAUSE@77..104
         0: TYPE_KW@77..82 "type" [] [Whitespace(" ")]
-        1: JS_NAMESPACE_IMPORT_SPECIFIER@82..92
+        1: (empty)
+        2: JS_NAMESPACE_IMPORT_SPECIFIER@82..92
           0: STAR@82..84 "*" [] [Whitespace(" ")]
           1: AS_KW@84..87 "as" [] [Whitespace(" ")]
           2: JS_IDENTIFIER_BINDING@87..92
             0: IDENT@87..92 "foo2" [] [Whitespace(" ")]
-        2: FROM_KW@92..97 "from" [] [Whitespace(" ")]
-        3: JS_MODULE_SOURCE@97..104
+        3: FROM_KW@92..97 "from" [] [Whitespace(" ")]
+        4: JS_MODULE_SOURCE@97..104
           0: JS_STRING_LITERAL@97..104 "\"./mod\"" [] []
-        4: (empty)
+        5: (empty)
       2: SEMICOLON@104..105 ";" [] []
     3: JS_IMPORT@105..138
       0: IMPORT_KW@105..113 "import" [Newline("\n")] [Whitespace(" ")]