在ES6中，如何检查对象的类？

In the ES6, if I make a class and create an object of that class, how do I check that the object is that class?

在ES6中,如果我创建一个类并创建该类的对象,我该如何检查该对象是否是该类?

I can't just use typeof because the objects are still "object". Do I just compare constructors?

我不能只使用typeof因为对象仍然是“对象”。我只是比较构造函数吗?

Example:

class Person {
  constructor() {}
}

var person = new Person();

if ( /* what do I put here to check if person is a Person? */ ) {
  // do stuff
}

3 个解决方案

#1

Can't you do person instanceof Person?

你不能做人的实例吗?

Comparing constructors alone won't work for subclasses

单独比较构造函数不适用于子类

#2

Just a word of caution, the use of instanceof seems prone to failure for literals of built-in JS classes (e.g. String, Number, etc). In these cases it might be safer to use typeof as follows:

需要注意的是,使用instanceof似乎很容易导致内置JS类的文字失败(例如String,Number等)。在这些情况下,使用typeof可能更安全,如下所示:

typeof("foo") === "string";

typeof(“foo”)===“string”;

Refer to this thread for more info.

有关详细信息,请参阅此主题。

#3

-3

in case of ecmascript-6 classes inheritance: lets say class A is base for B and C, then neither instanceof nor typeof will work correctly, as

在ecmascript-6类继承的情况下:假设类A是B和C的基础,那么instanceof和typeof都不会正常工作,如

(new B()) instanceof C // is true

will return true. For this case, I am doing:

将返回true。对于这种情况,我正在做:

(new B()).constructor == B

Edit: instanceof works for mentioned case as well, my example code had issue.

编辑:instanceof也适用于上述案例,我的示例代码有问题。

#1