feat(minifier): fold typeof foo != "undefined" into `typeof foo < "…

…u"` (#8159)
oxc-project · Dec 28, 2024 · f3a36e1 · f3a36e1
1 parent 65796c4
commit f3a36e1
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Showing 2 changed files with 38 additions and 14 deletions.
diff --git a/crates/oxc_minifier/src/ast_passes/peephole_substitute_alternate_syntax.rs b/crates/oxc_minifier/src/ast_passes/peephole_substitute_alternate_syntax.rs
@@ -240,14 +240,24 @@ impl<'a, 'b> PeepholeSubstituteAlternateSyntax {
     }
 
     /// Compress `typeof foo == "undefined"` into `typeof foo > "u"`
+    ///
+    /// - `typeof foo == "undefined"` -> `typeof foo > "u"`
+    /// - `typeof foo != "undefined"` -> `typeof foo < "u"`
+    ///
     /// Enabled by `compress.typeofs`
     fn try_compress_typeof_undefined(
         expr: &mut BinaryExpression<'a>,
         ctx: Ctx<'a, 'b>,
     ) -> Option<Expression<'a>> {
-        if !matches!(expr.operator, BinaryOperator::Equality | BinaryOperator::StrictEquality) {
-            return None;
-        }
+        let new_op = match expr.operator {
+            BinaryOperator::Equality | BinaryOperator::StrictEquality => {
+                BinaryOperator::GreaterThan
+            }
+            BinaryOperator::Inequality | BinaryOperator::StrictInequality => {
+                BinaryOperator::LessThan
+            }
+            _ => return None,
+        };
         let pair = Self::commutative_pair(
             (&expr.left, &expr.right),
             |a| a.is_specific_string_literal("undefined").then_some(()),
@@ -266,7 +276,7 @@ impl<'a, 'b> PeepholeSubstituteAlternateSyntax {
         let argument = Expression::Identifier(ctx.alloc(id_ref));
         let left = ctx.ast.expression_unary(SPAN, UnaryOperator::Typeof, argument);
         let right = ctx.ast.expression_string_literal(SPAN, "u", None);
-        Some(ctx.ast.expression_binary(expr.span, left, BinaryOperator::GreaterThan, right))
+        Some(ctx.ast.expression_binary(expr.span, left, new_op, right))
     }
 
     /// Compress `foo === null || foo === undefined` into `foo == null`.
@@ -1143,6 +1153,20 @@ mod test {
         test_same("const foo = () => { foo; return 'baz' }");
     }
 
+    /// Port from <https://github.com/evanw/esbuild/blob/v0.24.2/internal/js_parser/js_parser_test.go#L4658>
+    #[test]
+    fn test_fold_is_typeof_equals_undefined() {
+        test("typeof x !== 'undefined'", "typeof x < 'u'");
+        test("typeof x != 'undefined'", "typeof x < 'u'");
+        test("'undefined' !== typeof x", "typeof x < 'u'");
+        test("'undefined' != typeof x", "typeof x < 'u'");
+
+        test("typeof x === 'undefined'", "typeof x > 'u'");
+        test("typeof x == 'undefined'", "typeof x > 'u'");
+        test("'undefined' === typeof x", "typeof x > 'u'");
+        test("'undefined' == typeof x", "typeof x > 'u'");
+    }
+
     #[test]
     fn test_fold_is_null_or_undefined() {
         test("foo === null || foo === undefined", "foo == null");

diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
@@ -3,25 +3,25 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 -------------------------------------------------------------------------------------
 72.14 kB   | 23.74 kB   | 23.70 kB   | 8.61 kB    | 8.54 kB    | react.development.js
 
-173.90 kB  | 60.22 kB   | 59.82 kB   | 19.49 kB   | 19.33 kB   | moment.js 
+173.90 kB  | 60.16 kB   | 59.82 kB   | 19.49 kB   | 19.33 kB   | moment.js 
 
-287.63 kB  | 90.61 kB   | 90.07 kB   | 32.19 kB   | 31.95 kB   | jquery.js 
+287.63 kB  | 90.59 kB   | 90.07 kB   | 32.19 kB   | 31.95 kB   | jquery.js 
 
-342.15 kB  | 118.76 kB  | 118.14 kB  | 44.54 kB   | 44.37 kB   | vue.js    
+342.15 kB  | 118.61 kB  | 118.14 kB  | 44.54 kB   | 44.37 kB   | vue.js    
 
 544.10 kB  | 72.04 kB   | 72.48 kB   | 26.18 kB   | 26.20 kB   | lodash.js 
 
-555.77 kB  | 273.90 kB  | 270.13 kB  | 91.19 kB   | 90.80 kB   | d3.js     
+555.77 kB  | 273.89 kB  | 270.13 kB  | 91.18 kB   | 90.80 kB   | d3.js     
 
-1.01 MB    | 461.13 kB  | 458.89 kB  | 126.91 kB  | 126.71 kB  | bundle.min.js
+1.01 MB    | 461.09 kB  | 458.89 kB  | 126.91 kB  | 126.71 kB  | bundle.min.js
 
-1.25 MB    | 656.81 kB  | 646.76 kB  | 164.16 kB  | 163.73 kB  | three.js  
+1.25 MB    | 656.66 kB  | 646.76 kB  | 164.14 kB  | 163.73 kB  | three.js  
 
-2.14 MB    | 735.33 kB  | 724.14 kB  | 180.99 kB  | 181.07 kB  | victory.js
+2.14 MB    | 735.28 kB  | 724.14 kB  | 180.98 kB  | 181.07 kB  | victory.js
 
-3.20 MB    | 1.01 MB    | 1.01 MB    | 332.27 kB  | 331.56 kB  | echarts.js
+3.20 MB    | 1.01 MB    | 1.01 MB    | 332.23 kB  | 331.56 kB  | echarts.js
 
-6.69 MB    | 2.36 MB    | 2.31 MB    | 495.04 kB  | 488.28 kB  | antd.js   
+6.69 MB    | 2.36 MB    | 2.31 MB    | 494.93 kB  | 488.28 kB  | antd.js   
 
-10.95 MB   | 3.51 MB    | 3.49 MB    | 910.93 kB  | 915.50 kB  | typescript.js
+10.95 MB   | 3.51 MB    | 3.49 MB    | 910.92 kB  | 915.50 kB  | typescript.js