diff --git a/napi/parser/src/lib.rs b/napi/parser/src/lib.rs
index fbca1d0ea4ce1..d219918848ed2 100644
--- a/napi/parser/src/lib.rs
+++ b/napi/parser/src/lib.rs
@@ -56,7 +56,7 @@ fn parse<'a>(
     let source_type = options
         .source_filename
         .as_ref()
-        .map(|name| SourceType::from_path(name).unwrap())
+        .and_then(|name| SourceType::from_path(name).ok())
         .unwrap_or_default();
     let source_type = match options.source_type.as_deref() {
         Some("script") => source_type.with_script(true),
diff --git a/napi/transform/src/isolated_declaration.rs b/napi/transform/src/isolated_declaration.rs
new file mode 100644
index 0000000000000..d3dc14794aed7
--- /dev/null
+++ b/napi/transform/src/isolated_declaration.rs
@@ -0,0 +1,42 @@
+use std::sync::Arc;
+
+use napi_derive::napi;
+
+use oxc_allocator::Allocator;
+use oxc_codegen::CodeGenerator;
+use oxc_diagnostics::{Error, NamedSource};
+use oxc_isolated_declarations::IsolatedDeclarations;
+use oxc_parser::Parser;
+use oxc_span::SourceType;
+
+#[napi(object)]
+pub struct IsolatedDeclarationsResult {
+    pub source_text: String,
+    pub errors: Vec<String>,
+}
+
+/// TypeScript Isolated Declarations for Standalone DTS Emit
+#[allow(clippy::needless_pass_by_value)]
+#[napi]
+pub fn isolated_declaration(filename: String, source_text: String) -> IsolatedDeclarationsResult {
+    let source_type = SourceType::from_path(&filename).unwrap_or_default().with_typescript(true);
+    let allocator = Allocator::default();
+    let parser_ret = Parser::new(&allocator, &source_text, source_type).parse();
+    let transformed_ret = IsolatedDeclarations::new(&allocator).build(&parser_ret.program);
+    let printed = CodeGenerator::new().build(&transformed_ret.program).source_text;
+
+    let mut errors = vec![];
+    if !parser_ret.errors.is_empty() || !transformed_ret.errors.is_empty() {
+        let source = Arc::new(NamedSource::new(filename, source_text.to_string()));
+        errors.extend(
+            parser_ret
+                .errors
+                .into_iter()
+                .chain(transformed_ret.errors)
+                .map(|diagnostic| Error::from(diagnostic).with_source_code(Arc::clone(&source)))
+                .map(|error| format!("{error:?}")),
+        );
+    }
+
+    IsolatedDeclarationsResult { source_text: printed, errors }
+}
diff --git a/napi/transform/src/lib.rs b/napi/transform/src/lib.rs
index 99bfeab129814..37cec7e610364 100644
--- a/napi/transform/src/lib.rs
+++ b/napi/transform/src/lib.rs
@@ -1,44 +1,4 @@
-pub mod transformer;
+mod isolated_declaration;
+mod transformer;
 
-use std::sync::Arc;
-
-use napi_derive::napi;
-
-use oxc_allocator::Allocator;
-use oxc_codegen::CodeGenerator;
-use oxc_diagnostics::{Error, NamedSource};
-use oxc_isolated_declarations::IsolatedDeclarations;
-use oxc_parser::Parser;
-use oxc_span::SourceType;
-
-#[napi(object)]
-pub struct IsolatedDeclarationsResult {
-    pub source_text: String,
-    pub errors: Vec<String>,
-}
-
-/// TypeScript Isolated Declarations for Standalone DTS Emit
-#[allow(clippy::needless_pass_by_value)]
-#[napi]
-pub fn isolated_declaration(filename: String, source_text: String) -> IsolatedDeclarationsResult {
-    let source_type = SourceType::from_path(&filename).unwrap_or_default().with_typescript(true);
-    let allocator = Allocator::default();
-    let parser_ret = Parser::new(&allocator, &source_text, source_type).parse();
-    let transformed_ret = IsolatedDeclarations::new(&allocator).build(&parser_ret.program);
-    let printed = CodeGenerator::new().build(&transformed_ret.program).source_text;
-
-    let mut errors = vec![];
-    if !parser_ret.errors.is_empty() || !transformed_ret.errors.is_empty() {
-        let source = Arc::new(NamedSource::new(filename, source_text.to_string()));
-        errors.extend(
-            parser_ret
-                .errors
-                .into_iter()
-                .chain(transformed_ret.errors)
-                .map(|diagnostic| Error::from(diagnostic).with_source_code(Arc::clone(&source)))
-                .map(|error| format!("{error:?}")),
-        );
-    }
-
-    IsolatedDeclarationsResult { source_text: printed, errors }
-}
+pub use crate::{isolated_declaration::*, transformer::*};
diff --git a/napi/transform/src/transformer.rs b/napi/transform/src/transformer.rs
index de82c804a0e42..5d9841b58cfce 100644
--- a/napi/transform/src/transformer.rs
+++ b/napi/transform/src/transformer.rs
@@ -1,13 +1,14 @@
 use std::path::Path;
 
 use napi_derive::napi;
+
 use oxc_allocator::Allocator;
 use oxc_codegen::CodeGenerator;
 use oxc_parser::Parser;
 use oxc_span::SourceType;
 use oxc_transformer::{
-    ArrowFunctionsOptions, ES2015Options, ReactJsxRuntime, ReactOptions, TransformOptions,
-    Transformer, TypeScriptOptions,
+    ArrowFunctionsOptions, ES2015Options, ReactJsxRuntime, ReactOptions, Transformer,
+    TypeScriptOptions,
 };
 
 #[napi(object)]
@@ -92,7 +93,9 @@ impl From<ES2015BindingOptions> for ES2015Options {
 }
 
 #[napi(object)]
-pub struct TransformBindingOptions {
+pub struct TransformOptions {
+    #[napi(ts_type = "'script' | 'module' | 'unambiguous' | undefined")]
+    pub source_type: Option<String>,
     pub typescript: Option<TypeScriptBindingOptions>,
     pub react: Option<ReactBindingOptions>,
     pub es2015: Option<ES2015BindingOptions>,
@@ -104,13 +107,13 @@ pub struct TransformBindingOptions {
     pub sourcemap: Option<bool>,
 }
 
-impl From<TransformBindingOptions> for TransformOptions {
-    fn from(options: TransformBindingOptions) -> Self {
-        TransformOptions {
+impl From<TransformOptions> for oxc_transformer::TransformOptions {
+    fn from(options: TransformOptions) -> Self {
+        Self {
             typescript: options.typescript.map(Into::into).unwrap_or_default(),
             react: options.react.map(Into::into).unwrap_or_default(),
             es2015: options.es2015.map(Into::into).unwrap_or_default(),
-            ..TransformOptions::default()
+            ..Self::default()
         }
     }
 }
@@ -137,13 +140,18 @@ pub struct TransformResult {
 pub fn transform(
     filename: String,
     source_text: String,
-    options: Option<TransformBindingOptions>,
+    options: Option<TransformOptions>,
 ) -> TransformResult {
     let sourcemap = options.as_ref().is_some_and(|x| x.sourcemap.unwrap_or_default());
     let mut errors = vec![];
 
-    let source_path = Path::new(&filename);
-    let source_type = SourceType::from_path(source_path).unwrap_or_default();
+    let source_type = SourceType::from_path(&filename).unwrap_or_default();
+    let source_type = match options.as_ref().and_then(|options| options.source_type.as_deref()) {
+        Some("script") => source_type.with_script(true),
+        Some("module") => source_type.with_module(true),
+        _ => source_type,
+    };
+
     let allocator = Allocator::default();
     let parser_ret = Parser::new(&allocator, &source_text, source_type).parse();
     if !parser_ret.errors.is_empty() {
@@ -154,7 +162,7 @@ pub fn transform(
     let transform_options = options.map(Into::into).unwrap_or_default();
     let ret = Transformer::new(
         &allocator,
-        source_path,
+        Path::new(&filename),
         source_type,
         &source_text,
         parser_ret.trivias.clone(),
@@ -168,7 +176,7 @@ pub fn transform(
 
     let mut codegen = CodeGenerator::new();
     if sourcemap {
-        codegen = codegen.enable_source_map(source_path.to_string_lossy().as_ref(), &source_text);
+        codegen = codegen.enable_source_map(&filename, &source_text);
     }
     let ret = codegen.build(&program);