javascript - 为什么 Array.prototype 是一个数组？

Question

我认为每个原型(prototype)都应该是一个对象。

为什么？

Array.isArray( Array.prototype )//真

developer.mozilla.org什么都不解释

Answer 1

您假设每个原型(prototype)都是一个 Object 是不正确的。

console.log(String.prototype)
console.log(Number.prototype)
console.log(Boolean.prototype)
console.log(Array.prototype)
console.log(Object.prototype)

输出:

String {}
Number {}
Boolean {}
[]
Object {}

来自ECMAScript Language Specification - 15.4.4 Properties of the Array Prototype Object (强调我的)

The value of the [[Prototype]] internal property of the Array prototype object is the standard built-in Object prototype object (15.2.4).

The Array prototype object is itself an array; its [[Class]] is "Array", and it has a length property (whose initial value is +0) and the special [[DefineOwnProperty]] internal method described in 15.4.5.1.