diff --git a/crates/swc_webpack_ast/scripts/test-next.sh b/crates/swc_webpack_ast/scripts/test-next.sh
index 381b9001afa..d6924866ac1 100755
--- a/crates/swc_webpack_ast/scripts/test-next.sh
+++ b/crates/swc_webpack_ast/scripts/test-next.sh
@@ -9,6 +9,7 @@ export RUST_BACKTRACE=1
 cargo test --no-run
 UPDATE=1 cargo test -q
 
-(cd next.js/packages/next-swc && yarn build-native)
+(cd next.js/packages/next-swc && yarn build-native --release)
 
-(cd next.js && NEXT_PRIVATE_LOCAL_WEBPACK5=1 yarn next dev test/integration/production)
+(cd next.js && NEXT_PRIVATE_LOCAL_WEBPACK5=1 yarn testheadless $@ || true)
+(cd next.js && NEXT_PRIVATE_LOCAL_WEBPACK5=1 yarn next dev $@)
diff --git a/crates/swc_webpack_ast/src/lib.rs b/crates/swc_webpack_ast/src/lib.rs
index 14f94b398e6..3dae40737f5 100644
--- a/crates/swc_webpack_ast/src/lib.rs
+++ b/crates/swc_webpack_ast/src/lib.rs
@@ -1,7 +1,12 @@
 use crate::reducer::ast_reducer;
-use anyhow::{Context, Error};
-use swc_common::{sync::Lrc, Mark, SourceFile, SourceMap};
+use anyhow::{anyhow, Context, Error};
+use serde::Serialize;
+use swc_common::{
+    errors::HANDLER, sync::Lrc, FileName, FilePathMapping, Globals, Mark, SourceFile, SourceMap,
+    GLOBALS,
+};
 use swc_ecma_ast::*;
+use swc_ecma_parser::{lexer::Lexer, EsConfig, Parser, StringInput, Syntax, TsConfig};
 use swc_ecma_transforms_base::resolver::resolver_with_mark;
 use swc_ecma_visit::VisitMutWith;
 use swc_estree_ast::flavor::Flavor;
@@ -10,6 +15,73 @@ use swc_timer::timer;
 
 pub mod reducer;
 
+#[derive(Serialize)]
+pub struct AstOutput {
+    ast: String,
+    src: Option<Lrc<String>>,
+}
+
+pub fn process_file<F>(load_file: F, include_src: bool) -> Result<AstOutput, Error>
+where
+    F: FnOnce(&Lrc<SourceMap>) -> Result<Lrc<SourceFile>, Error>,
+{
+    let globals = Globals::new();
+    let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+
+    let fm = load_file(&cm).context("failed to load file")?;
+
+    // Default
+    let syntax = Syntax::Es(EsConfig {
+        jsx: true,
+        ..Default::default()
+    });
+    let syntax = match &fm.name {
+        FileName::Real(path) => match path.extension() {
+            Some(ext) => {
+                if ext == "tsx" {
+                    Syntax::Typescript(TsConfig {
+                        tsx: true,
+                        no_early_errors: true,
+                        ..Default::default()
+                    })
+                } else if ext == "ts" {
+                    Syntax::Typescript(TsConfig {
+                        no_early_errors: true,
+                        ..Default::default()
+                    })
+                } else {
+                    syntax
+                }
+            }
+            _ => syntax,
+        },
+        _ => syntax,
+    };
+
+    let module = {
+        let lexer = Lexer::new(syntax, EsVersion::latest(), StringInput::from(&*fm), None);
+        let mut parser = Parser::new_from(lexer);
+
+        parser.parse_module().map_err(|err| {
+            HANDLER.with(|h| {
+                err.into_diagnostic(h).emit();
+                anyhow!("failed to parse module")
+            })
+        })?
+    };
+
+    let ast = GLOBALS.set(&globals, || webpack_ast(cm.clone(), fm.clone(), module))?;
+
+    Ok(AstOutput {
+        ast,
+        src: if include_src {
+            Some(fm.src.clone())
+        } else {
+            None
+        },
+    })
+}
+
 /// `n` is expected to be pure (`resolver` is not applied)
 pub fn webpack_ast(
     cm: Lrc<SourceMap>,
@@ -27,6 +99,7 @@ pub fn webpack_ast(
             let _timer = timer!("resolver");
             n.visit_mut_with(&mut resolver_with_mark(top_level_mark));
         }
+
         {
             n.visit_mut_with(&mut ast_reducer(top_level_mark));
         }
diff --git a/crates/swc_webpack_ast/src/reducer/mod.rs b/crates/swc_webpack_ast/src/reducer/mod.rs
index 35f468a6f2b..6a70e085f8e 100644
--- a/crates/swc_webpack_ast/src/reducer/mod.rs
+++ b/crates/swc_webpack_ast/src/reducer/mod.rs
@@ -1,11 +1,11 @@
-use self::flatten::contains_import;
+use self::{flatten::contains_import, typescript::ts_remover};
 use std::{iter::once, sync::Arc};
 use swc_atoms::js_word;
 use swc_common::{
-    collections::AHashSet,
+    collections::{AHashMap, AHashSet},
     pass::{Repeat, Repeated},
     util::take::Take,
-    Mark, Span, Spanned, SyntaxContext,
+    Mark, Span, Spanned, SyntaxContext, DUMMY_SP,
 };
 use swc_ecma_ast::*;
 use swc_ecma_utils::{ident::IdentLike, Id, IsEmpty, StmtLike, StmtOrModuleItem};
@@ -13,6 +13,7 @@ use swc_ecma_visit::{Visit, VisitMut, VisitMutWith, VisitWith};
 use swc_timer::timer;
 
 mod flatten;
+mod typescript;
 
 /// # Usage
 ///
@@ -68,11 +69,24 @@ pub fn ast_reducer(top_level_mark: Mark) -> impl VisitMut {
     })
 }
 
+#[derive(Debug, Clone, Copy, Default)]
+struct BindingInfo {
+    used_as_type: bool,
+    used_as_var: bool,
+}
+
 struct Analyzer {
     amd_requires: AHashSet<Id>,
+    used_refs: AHashMap<Id, BindingInfo>,
 }
 
 impl Visit for Analyzer {
+    fn visit_assign_pat_prop(&mut self, p: &AssignPatProp) {
+        p.visit_children_with(self);
+
+        self.used_refs.entry(p.key.to_id()).or_default().used_as_var = true;
+    }
+
     fn visit_call_expr(&mut self, e: &CallExpr) {
         e.visit_children_with(self);
 
@@ -124,6 +138,64 @@ impl Visit for Analyzer {
             _ => {}
         }
     }
+
+    fn visit_expr(&mut self, e: &Expr) {
+        e.visit_children_with(self);
+
+        match e {
+            Expr::Ident(i) => {
+                self.used_refs.entry(i.to_id()).or_default().used_as_var = true;
+            }
+
+            _ => {}
+        }
+    }
+
+    fn visit_member_expr(&mut self, e: &MemberExpr) {
+        e.obj.visit_with(self);
+
+        if e.computed {
+            e.prop.visit_with(self);
+        }
+    }
+
+    fn visit_pat(&mut self, p: &Pat) {
+        p.visit_children_with(self);
+
+        match p {
+            Pat::Ident(s) => {
+                self.used_refs.entry(s.to_id()).or_default().used_as_var = true;
+            }
+
+            _ => {}
+        }
+    }
+
+    fn visit_prop(&mut self, p: &Prop) {
+        p.visit_children_with(self);
+
+        match p {
+            Prop::Shorthand(s) => {
+                self.used_refs.entry(s.to_id()).or_default().used_as_var = true;
+            }
+
+            _ => {}
+        }
+    }
+
+    fn visit_ts_type_ref(&mut self, ty: &TsTypeRef) {
+        fn left_most(n: &TsEntityName) -> &Ident {
+            match n {
+                TsEntityName::Ident(i) => i,
+                TsEntityName::TsQualifiedName(q) => left_most(&q.left),
+            }
+        }
+
+        ty.visit_children_with(self);
+
+        let left = left_most(&ty.type_name);
+        self.used_refs.entry(left.to_id()).or_default().used_as_type = true;
+    }
 }
 
 #[derive(Default)]
@@ -131,6 +203,9 @@ struct ScopeData {
     imported_ids: AHashSet<Id>,
     /// amd `require` modules.
     amd_requires: AHashSet<Id>,
+
+    #[allow(unused)]
+    used_refs: AHashMap<Id, BindingInfo>,
 }
 
 impl ScopeData {
@@ -160,7 +235,8 @@ impl ScopeData {
         }
 
         let mut analyzer = Analyzer {
-            amd_requires: AHashSet::default(),
+            amd_requires: Default::default(),
+            used_refs: Default::default(),
         };
 
         items.visit_with(&mut analyzer);
@@ -168,6 +244,7 @@ impl ScopeData {
         ScopeData {
             imported_ids,
             amd_requires: analyzer.amd_requires,
+            used_refs: analyzer.used_refs,
         }
     }
 
@@ -791,22 +868,6 @@ impl VisitMut for ReduceAst {
                 *e = *expr.arg.take();
             }
 
-            Expr::TsAs(expr) => {
-                *e = *expr.expr.take();
-            }
-
-            Expr::TsConstAssertion(expr) => {
-                *e = *expr.expr.take();
-            }
-
-            Expr::TsTypeAssertion(expr) => {
-                *e = *expr.expr.take();
-            }
-
-            Expr::TsNonNull(expr) => {
-                *e = *expr.expr.take();
-            }
-
             Expr::TaggedTpl(expr) => {
                 let mut exprs = Vec::with_capacity(expr.tpl.exprs.len() + 1);
                 exprs.push(expr.tag.take());
@@ -1318,9 +1379,17 @@ impl VisitMut for ReduceAst {
 
     fn visit_mut_module_items(&mut self, stmts: &mut Vec<ModuleItem>) {
         if !self.collected_data {
-            let _timer = timer!("analyze before reducing");
             self.collected_data = true;
-            self.data = Arc::new(ScopeData::analyze(&stmts));
+
+            {
+                let _timer = timer!("analyze before reducing");
+                self.data = Arc::new(ScopeData::analyze(&stmts));
+            }
+            {
+                let _timer = timer!("remove typescript nodes");
+
+                stmts.visit_mut_with(&mut ts_remover());
+            }
         }
 
         let _timer = timer!("reduce ast (single pass)");
@@ -1438,7 +1507,12 @@ impl VisitMut for ReduceAst {
         }
 
         match pat {
-            Pat::Assign(..) => {}
+            Pat::Assign(..) => {
+                let old = self.can_remove_pat;
+                self.can_remove_pat = false;
+                pat.visit_mut_children_with(self);
+                self.can_remove_pat = old;
+            }
             _ => {
                 pat.visit_mut_children_with(self);
             }
@@ -1566,7 +1640,7 @@ impl VisitMut for ReduceAst {
     fn visit_mut_stmt(&mut self, stmt: &mut Stmt) {
         match stmt {
             Stmt::Debugger(_) | Stmt::Break(_) | Stmt::Continue(_) => {
-                *stmt = Stmt::Empty(EmptyStmt { span: stmt.span() });
+                *stmt = Stmt::Empty(EmptyStmt { span: DUMMY_SP });
                 return;
             }
 
diff --git a/crates/swc_webpack_ast/src/reducer/typescript.rs b/crates/swc_webpack_ast/src/reducer/typescript.rs
new file mode 100644
index 00000000000..a9eb83c8d16
--- /dev/null
+++ b/crates/swc_webpack_ast/src/reducer/typescript.rs
@@ -0,0 +1,106 @@
+use swc_common::util::take::Take;
+use swc_ecma_ast::*;
+use swc_ecma_visit::{VisitMut, VisitMutWith};
+
+pub fn ts_remover() -> impl VisitMut {
+    TsRemover {}
+}
+
+struct TsRemover {}
+
+impl VisitMut for TsRemover {
+    fn visit_mut_array_pat(&mut self, p: &mut ArrayPat) {
+        p.visit_mut_children_with(self);
+
+        p.optional = false;
+    }
+
+    fn visit_mut_expr(&mut self, e: &mut Expr) {
+        e.visit_mut_children_with(self);
+
+        match e {
+            Expr::TsAs(expr) => {
+                *e = *expr.expr.take();
+            }
+
+            Expr::TsConstAssertion(expr) => {
+                *e = *expr.expr.take();
+            }
+
+            Expr::TsTypeAssertion(expr) => {
+                *e = *expr.expr.take();
+            }
+
+            Expr::TsNonNull(expr) => {
+                *e = *expr.expr.take();
+            }
+
+            _ => {}
+        }
+    }
+
+    fn visit_mut_ident(&mut self, i: &mut Ident) {
+        i.visit_mut_children_with(self);
+
+        i.optional = false;
+    }
+
+    fn visit_mut_module_item(&mut self, s: &mut ModuleItem) {
+        s.visit_mut_children_with(self);
+
+        match s {
+            ModuleItem::ModuleDecl(ModuleDecl::ExportDecl(ExportDecl {
+                decl: Decl::TsInterface(_) | Decl::TsTypeAlias(_),
+                ..
+            }))
+            | ModuleItem::ModuleDecl(ModuleDecl::Import(ImportDecl {
+                type_only: true, ..
+            }))
+            | ModuleItem::ModuleDecl(ModuleDecl::ExportNamed(NamedExport {
+                type_only: true,
+                ..
+            })) => {
+                s.take();
+                return;
+            }
+            _ => {}
+        }
+    }
+
+    fn visit_mut_object_pat(&mut self, p: &mut ObjectPat) {
+        p.visit_mut_children_with(self);
+
+        p.optional = false;
+    }
+
+    fn visit_mut_opt_ts_type(&mut self, ty: &mut Option<Box<TsType>>) {
+        *ty = None;
+    }
+
+    fn visit_mut_opt_ts_type_ann(&mut self, ty: &mut Option<TsTypeAnn>) {
+        *ty = None;
+    }
+
+    fn visit_mut_opt_ts_type_param_decl(&mut self, t: &mut Option<TsTypeParamDecl>) {
+        *t = None;
+    }
+
+    fn visit_mut_opt_ts_type_param_instantiation(
+        &mut self,
+        t: &mut Option<TsTypeParamInstantiation>,
+    ) {
+        *t = None;
+    }
+
+    fn visit_mut_stmt(&mut self, s: &mut Stmt) {
+        s.visit_mut_children_with(self);
+
+        match s {
+            Stmt::Decl(Decl::TsTypeAlias(..) | Decl::TsInterface(..)) => {
+                s.take();
+            }
+
+            _ => {}
+        }
+    }
+}
diff --git a/crates/swc_webpack_ast/tests/fixture.rs b/crates/swc_webpack_ast/tests/fixture.rs
index ac02886a44b..27631203a35 100644
--- a/crates/swc_webpack_ast/tests/fixture.rs
+++ b/crates/swc_webpack_ast/tests/fixture.rs
@@ -1,5 +1,5 @@
 use std::{fs, path::PathBuf};
-use swc_common::{chain, Mark};
+use swc_common::{chain, Mark, Span};
 use swc_ecma_ast::*;
 use swc_ecma_parser::{EsConfig, Parser, StringInput, Syntax, TsConfig};
 use swc_ecma_transforms_base::resolver::resolver_with_mark;
@@ -33,14 +33,24 @@ fn fixture(input: PathBuf) {
 struct AssertValid;
 
 impl VisitMut for AssertValid {
+    fn visit_mut_array_pat(&mut self, a: &mut ArrayPat) {
+        if a.optional {
+            panic!("found an optional pattern: {:?}", a)
+        }
+
+        a.visit_mut_children_with(self);
+    }
+
     fn visit_mut_empty_stmt(&mut self, i: &mut EmptyStmt) {
         panic!("found empty: {:?}", i)
     }
 
     fn visit_mut_ident(&mut self, i: &mut Ident) {
-        if i.span.is_dummy() {
-            panic!("found an identifier with dummy span: {:?}", i)
+        if i.optional {
+            panic!("found an optional pattern: {:?}", i)
         }
+
+        i.visit_mut_children_with(self);
     }
 
     fn visit_mut_if_stmt(&mut self, s: &mut IfStmt) {
@@ -59,11 +69,27 @@ impl VisitMut for AssertValid {
     fn visit_mut_module(&mut self, m: &mut Module) {
         dbg!(&*m);
 
-        m.visit_mut_children_with(self);
+        m.body.visit_mut_with(self);
+    }
+
+    fn visit_mut_object_pat(&mut self, pat: &mut ObjectPat) {
+        if pat.optional {
+            panic!("found a optional pattern: {:?}", pat)
+        }
+
+        pat.visit_mut_children_with(self);
+    }
+
+    fn visit_mut_span(&mut self, sp: &mut Span) {
+        assert!(!sp.is_dummy());
+    }
+
+    fn visit_mut_ts_type(&mut self, ty: &mut TsType) {
+        panic!("found a typescript type: {:?}", ty)
     }
 }
 
-#[testing::fixture("../swc_ecma_parser/tests/typescript/tsc/**/input.ts")]
+#[testing::fixture("../swc_ecma_parser/tests/typescript/**/input.ts")]
 #[testing::fixture("../swc/tests/tsc-references/**/output.js")]
 fn assert_no_invalid(input: PathBuf) {
     testing::run_test(false, |cm, _handler| {
diff --git a/crates/swc_webpack_ast/tests/fixture/issue/1/output.js b/crates/swc_webpack_ast/tests/fixture/issue/1/output.js
index 7fe8d3dc1f8..d9e9f381463 100644
--- a/crates/swc_webpack_ast/tests/fixture/issue/1/output.js
+++ b/crates/swc_webpack_ast/tests/fixture/issue/1/output.js
@@ -53,8 +53,7 @@ class Container extends React.Component {
 }
 export const emitter = mitt();
 let CachedComponent;
-export async function initNext(opts = {
-}) {
+export async function initNext() {
     let initialErr;
     const appEntrypoint = null;
     const { component: app , exports: mod  } = null;
diff --git a/crates/swc_webpack_ast/tests/fixture/next/client/index/output.js b/crates/swc_webpack_ast/tests/fixture/next/client/index/output.js
index 1c5f6b6f424..b901efd7c6d 100644
--- a/crates/swc_webpack_ast/tests/fixture/next/client/index/output.js
+++ b/crates/swc_webpack_ast/tests/fixture/next/client/index/output.js
@@ -78,8 +78,7 @@ class Container {
 const emitter = null;
 exports.emitter = null;
 let CachedComponent;
-(function*(opts = {
-}) {
+(function*() {
     let initialErr;
     const appEntrypoint = null;
     const { component: app , exports: mod  } = null;