JS: fix bug when merging hoisted var-decl to let-decl, fixes #687

js/js_test.go

@@ -816,6 +816,7 @@ func TestJS(t *testing.T) {
  {`'\u000A\u000D'`, "`\n\r`"}, // #653
  {`for(!a;b;c);`, "for(!a;b;c);"}, // #656
  {"var a = /*! comment */ b;", "/*! comment */var a=b"}, // #664
+ {`var c="";for(let i=0;;);var d="";for(let i=0;;);`, `var d,c="";for(let i=0;;);d="";for(let i=0;;);`}, // #687
  }
 
  m := minify.New()

js/stmtlist.go

@@ -190,11 +190,15 @@ func optimizeStmtList(list []js.IStmt, blockType blockType) []js.IStmt {
  j--
  } else if forStmt, ok := list[i].(*js.ForStmt); ok {
  // TODO: only merge lhs expression that don't have 'in' or 'of' keywords (slow to check?)
- if varDecl, ok := forStmt.Init.(*js.VarDecl); ok {
- if len(varDecl.List) == 0 || forStmt.Init == nil {
- forStmt.Init = left.Value
- j--
- } else if mergeVarDeclExprStmt(varDecl, left, true) {
+ if forStmt.Init == nil {
+ forStmt.Init = left.Value
+ j--
+ } else if decl, ok := forStmt.Init.(*js.VarDecl); ok && len(decl.List) == 0 {
+ forStmt.Init = left.Value
+ j--
+ } else if ok && (decl.TokenType == js.VarToken || decl.TokenType == js.ErrorToken) {
+ // this is the second VarDecl, so we are hoisting var declarations, which means the forInit variables are already in 'left'
+ if merge := mergeVarDeclExprStmt(decl, left, true); merge {
  j--
  }
  }