JS: keep order of declaration for variable renaming of function argum…

…ents, improves GZIP compression
tdewolff · May 28, 2022 · 0be056c · 0be056c
1 parent a086566
commit 0be056c
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Showing 5 changed files with 8 additions and 7 deletions.
diff --git a/go.mod b/go.mod
@@ -9,6 +9,6 @@ require (
 	github.com/fsnotify/fsnotify v1.5.4
 	github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2
 	github.com/spf13/pflag v1.0.5
-	github.com/tdewolff/parse/v2 v2.5.31
+	github.com/tdewolff/parse/v2 v2.5.32
 	github.com/tdewolff/test v1.0.6
 )
diff --git a/go.sum b/go.sum
@@ -10,8 +10,8 @@ github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2 h1:JAEbJn3j/FrhdWA9jW8
 github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2/go.mod h1:0KeJpeMD6o+O4hW7qJOT7vyQPKrWmj26uf5wMc/IiIs=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
-github.com/tdewolff/parse/v2 v2.5.31 h1:PrJN/trWTUYaYxg7jRpKnKXpBK4kBjT9rAFhFAh2Lus=
-github.com/tdewolff/parse/v2 v2.5.31/go.mod h1:WzaJpRSbwq++EIQHYIRTpbYKNA3gn9it1Ik++q4zyho=
+github.com/tdewolff/parse/v2 v2.5.32 h1:paypOpwqGqCjzm/QpgZj8+J4O4glJpe2qCtzM9zffgY=
+github.com/tdewolff/parse/v2 v2.5.32/go.mod h1:WzaJpRSbwq++EIQHYIRTpbYKNA3gn9it1Ik++q4zyho=
 github.com/tdewolff/test v1.0.6 h1:76mzYJQ83Op284kMT+63iCNCI7NEERsIN8dLM+RiKr4=
 github.com/tdewolff/test v1.0.6/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
 golang.org/x/sys v0.0.0-20220412211240-33da011f77ad h1:ntjMns5wyP/fN65tdBD4g8J5w8n015+iIIs9rtjXkY0=

diff --git a/js/js.go b/js/js.go
@@ -422,7 +422,7 @@ func (m *jsMinifier) minifyBlockAsStmt(blockStmt *js.BlockStmt) {
 	// minify block when statement is expected, i.e. semicolon if empty or remove braces for single statement
 	// assume we already renamed the scope
 	hasLexicalVars := false
-	for _, v := range blockStmt.Scope.Declared[blockStmt.Scope.NumForDeclared:] {
+	for _, v := range blockStmt.Scope.Declared[blockStmt.Scope.NumForDecls:] {
 		if v.Decl == js.LexicalDecl {
 			hasLexicalVars = true
 			break

diff --git a/js/js_test.go b/js/js_test.go
@@ -820,7 +820,7 @@ func TestJSVarRenaming(t *testing.T) {
 		{`let a=0;switch(a){case 0:let b=1;case 1:let c=2}`, `let a=0;switch(a){case 0:let a=1;case 1:let b=2}`},
 		{`({a:b=1}={})=>b`, `({a=1}={})=>a`}, // #422
 		{`()=>{var a;if(x){const b=0;while(true);}}`, `()=>{if(x){const b=0;for(var a;!0;);}}`},
-		{`(e,s)=>{e=>0,s(e(s))}`, `(b,a)=>{a=>0,a(b(a))}`}, // #469
+		{`(e,s)=>{e=>0,s(e(s))}`, `(a,b)=>{a=>0,b(a(b))}`}, // #469
 	}
 
 	m := minify.New()

diff --git a/js/vars.go b/js/vars.go
@@ -46,7 +46,8 @@ func (r *renamer) renameScope(scope js.Scope) {
 	}
 
 	i := 0
-	sort.Sort(js.VarsByUses(scope.Declared))
+	// keep function argument declaration order to improve GZIP compression
+	sort.Sort(js.VarsByUses(scope.Declared[scope.NumFuncArgs:]))
 	for _, v := range scope.Declared {
 		v.Data = r.getName(v.Data, i)
 		i++
@@ -111,8 +112,8 @@ func (r *renamer) getName(name []byte, index int) []byte {
 		name[0] = r.identStart[index]
 		return name[:1]
 	}
-
 	index -= len(r.identStart)
+
 	n := 2
 	for {
 		offset := len(r.identStart)