fix #213: typeof must be followed by import type or entity name

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fix bug with TypeScript `typeof` operator ([#213](https://github.com/evanw/esbuild/issues/213))
+
+    The TypeScript parser in esbuild incorrectly treated `readonly` in `typeof readonly` as a type operator instead of an identifier, which meant that it expected a type expression to follow the `readonly` identifier. Type expressions containing `typeof readonly` are now parsed correctly.
+
 ## 0.5.18
 
 * Fix bug with code splitting and side effects

internal/parser/parser.go

@@ -994,9 +994,24 @@ func (p *parser) skipTypeScriptTypePrefix() {
 		}
 
 	case lexer.TTypeof:
-		// "typeof x"
 		p.lexer.Next()
-		p.skipTypeScriptType(ast.LPrefix)
+		if p.lexer.Token == lexer.TImport {
+			// "typeof import('fs')"
+			p.skipTypeScriptTypePrefix()
+		} else {
+			// "typeof x"
+			// "typeof x.y"
+			for {
+				if !p.lexer.IsIdentifierOrKeyword() {
+					p.lexer.Expected(lexer.TIdentifier)
+				}
+				p.lexer.Next()
+				if p.lexer.Token != lexer.TDot {
+					break
+				}
+				p.lexer.Next()
+			}
+		}
 
 	case lexer.TOpenBracket:
 		// "[number, string]"

internal/parser/parser_ts_test.go

@@ -138,6 +138,7 @@ func TestTSTypes(t *testing.T) {
 	expectPrintedTS(t, "let x = [1] as readonly [number]", "let x = [1];\n")
 	expectPrintedTS(t, "let x = 'x' as keyof typeof Foo", "let x = \"x\";\n")
 	expectPrintedTS(t, "let fs: typeof import('fs') = require('fs')", "let fs = require(\"fs\");\n")
+	expectPrintedTS(t, "let fs: typeof import('fs').exists = require('fs').exists", "let fs = require(\"fs\").exists;\n")
 	expectPrintedTS(t, "let x: <T>() => Foo<T>", "let x;\n")
 	expectPrintedTS(t, "let x: new <T>() => Foo<T>", "let x;\n")
 	expectPrintedTS(t, "let x: <T extends object>() => Foo<T>", "let x;\n")
@@ -149,6 +150,12 @@ func TestTSTypes(t *testing.T) {
 	expectPrintedTS(t, "type Foo<T> = {-readonly [P in keyof T]: T[P]}", "")
 	expectPrintedTS(t, "type Foo<T> = {+readonly [P in keyof T]: T[P]}", "")
 	expectPrintedTS(t, "const x: unique symbol = y", "const x = y;\n")
+	expectPrintedTS(t, "let x: typeof a = y", "let x = y;\n")
+	expectPrintedTS(t, "let x: typeof a.b = y", "let x = y;\n")
+	expectPrintedTS(t, "let x: typeof a.if = y", "let x = y;\n")
+	expectPrintedTS(t, "let x: typeof if.a = y", "let x = y;\n")
+	expectPrintedTS(t, "let x: typeof readonly = y", "let x = y;\n")
+	expectParseErrorTS(t, "let x: typeof readonly Array", "<stdin>: error: Expected \";\" but found \"Array\"\n")
 	expectPrintedTS(t, "let x: `y`", "let x;\n")
 	expectParseErrorTS(t, "let x: tag`y`", "<stdin>: error: Expected \";\" but found \"`y`\"\n")