JS: support 'PrivateIdentifier in ShiftExpression'

js/ast.go

@@ -150,7 +150,6 @@ func (v Var) JS(w io.Writer) {
 }
 
 // VarsByUses is sortable by uses in descending order.
-// TODO: write custom sorter for varsbyuses
 type VarsByUses VarArray
 
 func (vs VarsByUses) Len() int {

js/parse.go

@@ -1767,7 +1767,13 @@ func (p *Parser) parseExpression(prec OpPrec) IExpr {
 		template := p.parseTemplateLiteral(precLeft)
 		left = &template
 		p.in = prevIn
-		// TODO: private identifier for relational operators
+	case PrivateIdentifierToken:
+		left = &LiteralExpr{p.tt, p.data}
+		p.next()
+		if p.tt != InToken {
+			p.fail("relational expression", InToken)
+			return left
+		}
 	default:
 		p.fail("expression")
 		return nil

js/parse_test.go

@@ -317,6 +317,7 @@ func TestParse(t *testing.T) {
 		{"protected = 0", "Stmt(protected=0)"},
 		{"public = 0", "Stmt(public=0)"},
 		{"static = 0", "Stmt(static=0)"},
+		{"#x in a", "Stmt(#x in a)"},
 
 		// expression to arrow function parameters
 		{"x = (a,b,c) => {a++}", "Stmt(x=(Params(Binding(a), Binding(b), Binding(c)) => Stmt({ Stmt(a++) })))"},