<img src="https://user-images.githubusercontent.com/18660671/163696838-9d3417c7-b139-4438-a82f-e41c02120663.png" height= 600 width=600 /> <img src="https://user-images.githubusercontent.com/18660671/163696847-9d2a4d2b-4cb2-42f2-8d5c-df73a09fe550.png" height= 400 width=600 /> ``` const obj = { a: 1, b: 2 } Object.preventExtensions(obj); obj.a = 2; // 可修改 delete obj.b; // 可删除 obj.c = 3; // 不可拓展 console.log(obj); ```  # preventExtensions、freeze、seal区别 `freeze`:不可修改、不可删除、不可拓展 `seal`:可修改、不可删除、不可拓展 `preventExtensions`:可修改、可删除、不可拓展