feat(minifier): remove empty if statment if (test) {} -> test (#8336

)
oxc-project · Jan 8, 2025 · 6220e05 · 6220e05
1 parent a76dfae
commit 6220e05
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Showing 2 changed files with 27 additions and 5 deletions.
diff --git a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
@@ -174,13 +174,29 @@ impl<'a, 'b> PeepholeRemoveDeadCode {
                     self.changed = true;
                 }
             }
+            Some(Statement::BlockStatement(s)) if s.body.is_empty() => {
+                if_stmt.alternate = None;
+                self.changed = true;
+            }
             Some(Statement::EmptyStatement(_)) => {
                 if_stmt.alternate = None;
                 self.changed = true;
             }
             _ => {}
         }
 
+        // `if (test) {}` -> `test`
+        if if_stmt.alternate.is_none()
+            && match &if_stmt.consequent {
+                Statement::EmptyStatement(_) => true,
+                Statement::BlockStatement(s) => s.body.is_empty(),
+                _ => false,
+            }
+        {
+            let expr = ctx.ast.move_expression(&mut if_stmt.test);
+            return Some(ctx.ast.statement_expression(if_stmt.span, expr));
+        }
+
         match ctx.get_boolean_value(&if_stmt.test) {
             Some(true) => Some(ctx.ast.move_statement(&mut if_stmt.consequent)),
             Some(false) => {
@@ -712,4 +728,10 @@ mod test {
         fold("try {} catch (e) { foo() } finally { let x = bar() }", "{ let x = bar();}");
         fold("try {} catch () { } finally {}", "");
     }
+
+    #[test]
+    fn test_fold_if_statement() {
+        test("if (foo) {}", "foo");
+        test("if (foo) {} else {}", "foo");
+    }
 }
diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
@@ -7,7 +7,7 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 287.63 kB  | 90.04 kB   | 90.07 kB   | 32.06 kB   | 31.95 kB   | jquery.js 
 
-342.15 kB  | 118.15 kB  | 118.14 kB  | 44.51 kB   | 44.37 kB   | vue.js    
+342.15 kB  | 118.14 kB  | 118.14 kB  | 44.51 kB   | 44.37 kB   | vue.js    
 
 544.10 kB  | 71.75 kB   | 72.48 kB   | 26.16 kB   | 26.20 kB   | lodash.js 
 
@@ -17,11 +17,11 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 1.25 MB    | 652.56 kB  | 646.76 kB  | 163.52 kB  | 163.73 kB  | three.js  
 
-2.14 MB    | 725.98 kB  | 724.14 kB  | 180.13 kB  | 181.07 kB  | victory.js
+2.14 MB    | 726.04 kB  | 724.14 kB  | 180.15 kB  | 181.07 kB  | victory.js
 
-3.20 MB    | 1.01 MB    | 1.01 MB    | 331.80 kB  | 331.56 kB  | echarts.js
+3.20 MB    | 1.01 MB    | 1.01 MB    | 331.83 kB  | 331.56 kB  | echarts.js
 
-6.69 MB    | 2.32 MB    | 2.31 MB    | 492.75 kB  | 488.28 kB  | antd.js   
+6.69 MB    | 2.32 MB    | 2.31 MB    | 492.72 kB  | 488.28 kB  | antd.js   
 
-10.95 MB   | 3.50 MB    | 3.49 MB    | 908.36 kB  | 915.50 kB  | typescript.js
+10.95 MB   | 3.50 MB    | 3.49 MB    | 908.29 kB  | 915.50 kB  | typescript.js