javascript - ES2015 规范附录 E 中的此条目有何意义？

Question

ES2015 规范的附录 E 包含以下内容:

19.2.3.2: In ECMAScript 2015, the [[Prototype]] internal slot of a bound function is set to the [[GetPrototypeOf]] value of its target function. In the previous edition, [[Prototype]] was always set to %FunctionPrototype%.

这有什么意义？

来源:http://www.ecma-international.org/ecma-262/6.0/#sec-additions-and-changes-that-introduce-incompatibilities-with-prior-editions

Answer 1

在 ES2015 之前，只有单一类型的函数。 ES2015介绍了箭头函数、生成器函数和方法。生成器函数和类方法不一定以Function.prototype作为其原型(prototype)。例如:

9.2.6 GeneratorFunctionCreate (kind, ParameterList, Body, Scope, Strict)

1. Let functionPrototype be the intrinsic object %Generator%.
2. Let F be FunctionAllocate(functionPrototype, Strict, "generator").
3. Return FunctionInitialize(F, kind, ParameterList, Body, Scope).

这些函数的绑定(bind)版本可能应该“保留”原始函数的原型(prototype)。