feat(es/modules): Support allowTopLevelThis (#5086)

crates/swc_ecma_transforms_module/src/amd.rs

@@ -163,6 +163,7 @@ impl VisitMut for Amd {
         stmts.visit_mut_children_with(&mut ModuleRefRewriter {
             import_map,
             lazy_record: Default::default(),
+            allow_top_level_this: self.config.allow_top_level_this,
             is_global_this: true,
         });
 

crates/swc_ecma_transforms_module/src/common_js.rs

@@ -139,6 +139,7 @@ impl VisitMut for Cjs {
         stmts.visit_mut_children_with(&mut ModuleRefRewriter {
             import_map,
             lazy_record,
+            allow_top_level_this: self.config.allow_top_level_this,
             is_global_this: true,
         });
 

crates/swc_ecma_transforms_module/src/module_ref_rewriter.rs

@@ -35,6 +35,8 @@ pub(crate) struct ModuleRefRewriter {
 
     pub lazy_record: AHashSet<Id>,
 
+    pub allow_top_level_this: bool,
+
     pub is_global_this: bool,
 }
 
@@ -67,7 +69,7 @@ impl VisitMut for ModuleRefRewriter {
             }
 
             Expr::This(ThisExpr { span }) => {
-                if self.is_global_this {
+                if !self.allow_top_level_this && self.is_global_this {
                     *n = *undefined(*span);
                 }
             }

crates/swc_ecma_transforms_module/src/umd.rs

@@ -143,6 +143,7 @@ impl VisitMut for Umd {
         stmts.visit_mut_children_with(&mut ModuleRefRewriter {
             import_map,
             lazy_record: Default::default(),
+            allow_top_level_this: self.config.config.allow_top_level_this,
             is_global_this: true,
         });
 

crates/swc_ecma_transforms_module/src/util.rs

@@ -14,6 +14,8 @@ use swc_ecma_utils::{
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(deny_unknown_fields, rename_all = "camelCase")]
 pub struct Config {
+    #[serde(default)]
+    pub allow_top_level_this: bool,
     #[serde(default)]
     pub strict: bool,
     #[serde(default = "default_strict_mode")]
@@ -34,6 +36,7 @@ pub struct Config {
 impl Default for Config {
     fn default() -> Self {
         Config {
+            allow_top_level_this: false,
             strict: false,
             strict_mode: default_strict_mode(),
             lazy: Lazy::default(),

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/false/input.js

@@ -0,0 +1 @@
+export var v = this;

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/false/module.json

@@ -0,0 +1,3 @@
+{
+    "allowTopLevelThis": false
+}

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/false/output.amd.js

@@ -0,0 +1,14 @@
+define([
+    "require",
+    "exports"
+], function(require, exports) {
+    "use strict";
+    Object.defineProperty(exports, "__esModule", {
+        value: true
+    });
+    Object.defineProperty(exports, "v", {
+        enumerable: true,
+        get: ()=>v
+    });
+    var v = void 0;
+});

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/false/output.cjs

@@ -0,0 +1,9 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+Object.defineProperty(exports, "v", {
+    enumerable: true,
+    get: ()=>v
+});
+var v = void 0;

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/false/output.umd.js

@@ -0,0 +1,17 @@
+(function(global, factory) {
+    if (typeof module === "object" && typeof module.exports === "object") factory(exports);
+    else if (typeof define === "function" && define.amd) define([
+        "exports"
+    ], factory);
+    else if (global = typeof globalThis !== "undefined" ? globalThis : global || self) factory(global.input = {});
+})(this, function(exports) {
+    "use strict";
+    Object.defineProperty(exports, "__esModule", {
+        value: true
+    });
+    Object.defineProperty(exports, "v", {
+        enumerable: true,
+        get: ()=>v
+    });
+    var v = void 0;
+});

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/true/input.js

@@ -0,0 +1 @@
+export var v = this;

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/true/module.json

@@ -0,0 +1,3 @@
+{
+    "allowTopLevelThis": true
+}

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/true/output.amd.js

@@ -0,0 +1,14 @@
+define([
+    "require",
+    "exports"
+], function(require, exports) {
+    "use strict";
+    Object.defineProperty(exports, "__esModule", {
+        value: true
+    });
+    Object.defineProperty(exports, "v", {
+        enumerable: true,
+        get: ()=>v
+    });
+    var v = this;
+});

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/true/output.cjs

@@ -0,0 +1,9 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+Object.defineProperty(exports, "v", {
+    enumerable: true,
+    get: ()=>v
+});
+var v = this;

crates/swc_ecma_transforms_module/tests/fixture/common/allow-top-level-this/true/output.umd.js

@@ -0,0 +1,17 @@
+(function(global, factory) {
+    if (typeof module === "object" && typeof module.exports === "object") factory(exports);
+    else if (typeof define === "function" && define.amd) define([
+        "exports"
+    ], factory);
+    else if (global = typeof globalThis !== "undefined" ? globalThis : global || self) factory(global.input = {});
+})(this, function(exports) {
+    "use strict";
+    Object.defineProperty(exports, "__esModule", {
+        value: true
+    });
+    Object.defineProperty(exports, "v", {
+        enumerable: true,
+        get: ()=>v
+    });
+    var v = this;
+});