🏁 compatible with old browser (#1136)

src/sandbox/__tests__/proxySandbox.test.ts

@@ -287,6 +287,15 @@ test('bounded function should not be rebounded', () => {
   expect(isBoundedFunction(proxy.fn1)).toBeTruthy();
 });
 
+test('the prototype should be kept while we create a function with prototype on proxy', () => {
+  const proxy = new ProxySandbox('new-function').proxy as any;
+
+  function test() {}
+  proxy.fn = test;
+  expect(proxy.fn === test).toBeFalsy();
+  expect(proxy.fn.prototype).toBe(test.prototype);
+});
+
 test('some native window property was defined with getter in safari and firefox, and they will check the caller source', () => {
   Object.defineProperty(window, 'mockSafariGetterProperty', {
     get(this: Window) {

src/sandbox/common.ts

@@ -35,8 +35,11 @@ export function getTargetValue(target: any, value: any): any {
       boundValue[key] = value[key];
     }
 
-    // copy prototype, for performance reason, we use in operator to check rather than hasOwnProperty
+    // copy prototype if bound function not have
-    if ('prototype' in value) boundValue.prototype = value.prototype;
+    // mostly a bound function have no own prototype, but it not absolute in some old version browser, see https://github.com/umijs/qiankun/issues/1121
+    if (value.hasOwnProperty('prototype') && !boundValue.hasOwnProperty('prototype'))
+      boundValue.prototype = value.prototype;
+
     functionBoundedValueMap.set(value, boundValue);
     return boundValue;
   }