swiftwasm · kateinoigakukun · Jul 22, 2025 · Jul 22, 2025
diff --git a/Sources/JavaScriptKit/JSException.swift b/Sources/JavaScriptKit/JSException.swift
@@ -46,4 +46,12 @@ public struct JSException: Error, Equatable, CustomStringConvertible {
             self.stack = nil
         }
     }
+
+    /// Initializes a new JavaScript `Error` instance with a message and prepare it to be thrown.
+    ///
+    /// - Parameters:
+    ///   - message: The message to throw.
+    public init(message: String) {
+        self.init(JSError(message: message).jsValue)
+    }
 }
diff --git a/Tests/JavaScriptKitTests/JSExceptionTests.swift b/Tests/JavaScriptKitTests/JSExceptionTests.swift
@@ -0,0 +1,64 @@
+import XCTest
+import JavaScriptKit
+
+class JSExceptionTests: XCTestCase {
+    private func eval(_ code: String) -> JSValue {
+        return JSObject.global.eval!(code)
+    }
+
+    func testThrowingMethodCalls() {
+        let context = eval(
+            """
+            (() => ({
+                func1: () => { throw new Error(); },
+                func2: () => { throw 'String Error'; },
+                func3: () => { throw 3.0; },
+            }))()
+            """
+        ).object!
+
+        // MARK: Throwing method calls
+        XCTAssertThrowsError(try context.throwing.func1!()) { error in
+            XCTAssertTrue(error is JSException)
+            let errorObject = JSError(from: (error as! JSException).thrownValue)
+            XCTAssertNotNil(errorObject)
+        }
+
+        XCTAssertThrowsError(try context.throwing.func2!()) { error in
+            XCTAssertTrue(error is JSException)
+            let thrownValue = (error as! JSException).thrownValue
+            XCTAssertEqual(thrownValue.string, "String Error")
+        }
+
+        XCTAssertThrowsError(try context.throwing.func3!()) { error in
+            XCTAssertTrue(error is JSException)
+            let thrownValue = (error as! JSException).thrownValue
+            XCTAssertEqual(thrownValue.number, 3.0)
+        }
+    }
+
+    func testThrowingUnboundFunctionCalls() {
+        let jsThrowError = eval("() => { throw new Error(); }")
+        XCTAssertThrowsError(try jsThrowError.function!.throws()) { error in
+            XCTAssertTrue(error is JSException)
+            let errorObject = JSError(from: (error as! JSException).thrownValue)
+            XCTAssertNotNil(errorObject)
+        }
+    }
+
+    func testThrowingConstructorCalls() {
+        let Animal = JSObject.global.Animal.function!
+        XCTAssertNoThrow(try Animal.throws.new("Tama", 3, true))
+        XCTAssertThrowsError(try Animal.throws.new("Tama", -3, true)) { error in
+            XCTAssertTrue(error is JSException)
+            let errorObject = JSError(from: (error as! JSException).thrownValue)
+            XCTAssertNotNil(errorObject)
+        }
+    }
+
+    func testInitWithMessage() {
+        let message = "THIS IS AN ERROR MESSAGE"
+        let exception = JSException(message: message)
+        XCTAssertTrue(exception.description.contains(message))
+    }
+}
diff --git a/Tests/JavaScriptKitTests/JavaScriptKitTests.swift b/Tests/JavaScriptKitTests/JavaScriptKitTests.swift
@@ -423,64 +423,6 @@ class JavaScriptKitTests: XCTestCase {
         globalObject1.prop_1.nested_prop = originalProp1
     }
 
-    func testException() {
-        // ```js
-        // global.globalObject1 = {
-        //   ...
-        //   prop_9: {
-        //       func1: function () {
-        //           throw new Error();
-        //       },
-        //       func2: function () {
-        //           throw "String Error";
-        //       },
-        //       func3: function () {
-        //           throw 3.0
-        //       },
-        //   },
-        //   ...
-        // }
-        // ```
-        //
-        let globalObject1 = JSObject.global.globalObject1
-        let prop_9: JSValue = globalObject1.prop_9
-
-        // MARK: Throwing method calls
-        XCTAssertThrowsError(try prop_9.object!.throwing.func1!()) { error in
-            XCTAssertTrue(error is JSException)
-            let errorObject = JSError(from: (error as! JSException).thrownValue)
-            XCTAssertNotNil(errorObject)
-        }
-
-        XCTAssertThrowsError(try prop_9.object!.throwing.func2!()) { error in
-            XCTAssertTrue(error is JSException)
-            let thrownValue = (error as! JSException).thrownValue
-            XCTAssertEqual(thrownValue.string, "String Error")
-        }
-
-        XCTAssertThrowsError(try prop_9.object!.throwing.func3!()) { error in
-            XCTAssertTrue(error is JSException)
-            let thrownValue = (error as! JSException).thrownValue
-            XCTAssertEqual(thrownValue.number, 3.0)
-        }
-
-        // MARK: Simple function calls
-        XCTAssertThrowsError(try prop_9.func1.function!.throws()) { error in
-            XCTAssertTrue(error is JSException)
-            let errorObject = JSError(from: (error as! JSException).thrownValue)
-            XCTAssertNotNil(errorObject)
-        }
-
-        // MARK: Throwing constructor call
-        let Animal = JSObject.global.Animal.function!
-        XCTAssertNoThrow(try Animal.throws.new("Tama", 3, true))
-        XCTAssertThrowsError(try Animal.throws.new("Tama", -3, true)) { error in
-            XCTAssertTrue(error is JSException)
-            let errorObject = JSError(from: (error as! JSException).thrownValue)
-            XCTAssertNotNil(errorObject)
-        }
-    }
-
     func testSymbols() {
         let symbol1 = JSSymbol("abc")
         let symbol2 = JSSymbol("abc")

diff --git a/Tests/prelude.mjs b/Tests/prelude.mjs
@@ -159,17 +159,6 @@ function setupTestGlobals(global) {
         },
         prop_7: 3.14,
         prop_8: [0, , 2, 3, , , 6],
-        prop_9: {
-            func1: function () {
-                throw new Error();
-            },
-            func2: function () {
-                throw "String Error";
-            },
-            func3: function () {
-                throw 3.0;
-            },
-        },
         eval_closure: function (fn) {
             return fn(arguments[1]);
         },