Reflect.getPrototypeOf()

¥Syntax

Reflect.getPrototypeOf(target)

¥Parameters

target

要获取其原型的目标对象。

¥Return value

给定对象的原型，可能是一个对象或 null。

¥The prototype of the given object, which may be an object or null.

¥Exceptions

TypeError

如果 target 不是对象，则抛出该异常。

¥Description

Reflect.getPrototypeOf() 提供了检索对象原型的反射语义。与 Object.getPrototypeOf() 的唯一区别是非对象目标的处理方式。如果目标不是对象，则 Reflect.getPrototypeOf() 抛出 TypeError，而 Object.getPrototypeOf() 将其强制为对象。

¥Reflect.getPrototypeOf() provides the reflective semantic of retrieving the prototype of an object. The only difference with Object.getPrototypeOf() is how non-object targets are handled. Reflect.getPrototypeOf() throws a TypeError if the target is not an object, while Object.getPrototypeOf() coerces it to an object.

Reflect.getPrototypeOf() 调用 target 的 [[GetPrototypeOf]] 对象内部方法。

¥Reflect.getPrototypeOf() invokes the [[GetPrototypeOf]] object internal method of target.

¥Examples

¥Using Reflect.getPrototypeOf()

Reflect.getPrototypeOf({}); // Object.prototype
Reflect.getPrototypeOf(Object.prototype); // null
Reflect.getPrototypeOf(Object.create(null)); // null

¥Difference with Object.getPrototypeOf()

// Same result for Objects
Object.getPrototypeOf({}); // Object.prototype
Reflect.getPrototypeOf({}); // Object.prototype

// Both throw in ES5 for non-Objects
Object.getPrototypeOf("foo"); // Throws TypeError
Reflect.getPrototypeOf("foo"); // Throws TypeError

// In ES2015 only Reflect throws, Object coerces non-Objects
Object.getPrototypeOf("foo"); // String.prototype
Reflect.getPrototypeOf("foo"); // Throws TypeError

// To mimic the Object ES2015 behavior you need to coerce
Reflect.getPrototypeOf(Object("foo")); // String.prototype

¥See also

• core-js 中 Reflect.getPrototypeOf 的 Polyfill
• Reflect
• Object.getPrototypeOf()
• handler.getPrototypeOf()