diff --git a/crates/swc_ecma_ast/src/expr.rs b/crates/swc_ecma_ast/src/expr.rs
index 4c06e145c22..0d35fa2d8e8 100644
--- a/crates/swc_ecma_ast/src/expr.rs
+++ b/crates/swc_ecma_ast/src/expr.rs
@@ -642,6 +642,12 @@ impl Take for TaggedTpl {
 pub struct TplElement {
     pub span: Span,
     pub tail: bool,
+
+    /// This value is never used by `swc_ecma_codegen`, and this fact is
+    /// considered as a public API.
+    ///
+    /// If you are going to use codegen right after creating a [TplElement], you
+    /// don't have to worry about this value.
     pub cooked: Option<Str>,
     pub raw: Str,
 }
diff --git a/crates/swc_ecma_ast/src/lit.rs b/crates/swc_ecma_ast/src/lit.rs
index 8d8bbe79311..9c0a3593141 100644
--- a/crates/swc_ecma_ast/src/lit.rs
+++ b/crates/swc_ecma_ast/src/lit.rs
@@ -53,6 +53,16 @@ impl<'a> arbitrary::Arbitrary<'a> for BigInt {
     }
 }
 
+/// A string literal.
+///
+/// # Note
+///
+/// You have to use [StrKind::Synthesized] if you modify the `value` of [Str].
+/// This behavior is for preserving the original source code.
+///
+/// In other words, `swc_ecma_codegen` tries to preserve escapes or unicode
+/// characters in the original source code and you can opt-out of this by using
+/// [StrKind::Synthesized].
 #[ast_node("StringLiteral")]
 #[derive(Eq, Hash, EqIgnoreSpan)]
 pub struct Str {
diff --git a/crates/swc_ecma_transforms_module/src/rewriter.rs b/crates/swc_ecma_transforms_module/src/rewriter.rs
index efa19bd38bb..01a1cd70312 100644
--- a/crates/swc_ecma_transforms_module/src/rewriter.rs
+++ b/crates/swc_ecma_transforms_module/src/rewriter.rs
@@ -47,6 +47,8 @@ where
                                     })
                                     .unwrap();
 
+                                // This string literal is synthesized
+                                s.kind = Default::default();
                                 s.value = src;
                             }
                             _ => {}
diff --git a/crates/swc_ecma_transforms_typescript/examples/ts_to_js.rs b/crates/swc_ecma_transforms_typescript/examples/ts_to_js.rs
index 40a9a5f4be1..129f3f3de1f 100644
--- a/crates/swc_ecma_transforms_typescript/examples/ts_to_js.rs
+++ b/crates/swc_ecma_transforms_typescript/examples/ts_to_js.rs
@@ -8,7 +8,7 @@ use swc_common::{
     comments::SingleThreadedComments,
     errors::{ColorConfig, Handler},
     sync::Lrc,
-    Mark, SourceMap,
+    Globals, Mark, SourceMap, GLOBALS,
 };
 use swc_ecma_codegen::{text_writer::JsWriter, Emitter};
 use swc_ecma_parser::{lexer::Lexer, Parser, StringInput, Syntax, TsConfig};
@@ -56,34 +56,37 @@ fn main() {
         .map_err(|e| e.into_diagnostic(&handler).emit())
         .expect("failed to parse module.");
 
-    let top_level_mark = Mark::fresh(Mark::root());
+    let globals = Globals::default();
+    GLOBALS.set(&globals, || {
+        let top_level_mark = Mark::fresh(Mark::root());
 
-    // Optionally transforms decorators here before the resolver pass
-    // as it might produce runtime declarations.
+        // Optionally transforms decorators here before the resolver pass
+        // as it might produce runtime declarations.
 
-    // Conduct identifier scope analysis
-    let module = module.fold_with(&mut resolver_with_mark(top_level_mark));
+        // Conduct identifier scope analysis
+        let module = module.fold_with(&mut resolver_with_mark(top_level_mark));
 
-    // Remove typescript types
-    let module = module.fold_with(&mut strip(top_level_mark));
+        // Remove typescript types
+        let module = module.fold_with(&mut strip(top_level_mark));
 
-    // Fix up any identifiers with the same name, but different contexts
-    let module = module.fold_with(&mut hygiene());
+        // Fix up any identifiers with the same name, but different contexts
+        let module = module.fold_with(&mut hygiene());
 
-    // Ensure that we have enough parenthesis.
-    let module = module.fold_with(&mut fixer(Some(&comments)));
+        // Ensure that we have enough parenthesis.
+        let module = module.fold_with(&mut fixer(Some(&comments)));
 
-    let mut buf = vec![];
-    {
-        let mut emitter = Emitter {
-            cfg: swc_ecma_codegen::Config { minify: false },
-            cm: cm.clone(),
-            comments: Some(&comments),
-            wr: JsWriter::new(cm.clone(), "\n", &mut buf, None),
-        };
+        let mut buf = vec![];
+        {
+            let mut emitter = Emitter {
+                cfg: swc_ecma_codegen::Config { minify: false },
+                cm: cm.clone(),
+                comments: Some(&comments),
+                wr: JsWriter::new(cm.clone(), "\n", &mut buf, None),
+            };
 
-        emitter.emit_module(&module).unwrap();
-    }
+            emitter.emit_module(&module).unwrap();
+        }
 
-    println!("{}", String::from_utf8(buf).expect("non-utf8?"));
+        println!("{}", String::from_utf8(buf).expect("non-utf8?"));
+    })
 }