javascript - 是否有可能以某种方式替换作为函数参数的原始对象？

Question

function f(obj) {
    obj = _ => console.log(
        'LOCAL object was replaced, how to replace from the outer scope?');
}

f(fetch);

据我了解这是不可能的，但也许存在一些技巧？

Answer 1

不，你不能这样做。

相反，最好的选择是返回新对象，并在调用时重新分配:

function f(obj) {
    return _ => console.log(
        'LOCAL object was replaced, how to replace from the outer scope?');
}

fetch = f(fetch);

<小时/>

或者，您可以传入一个将目标对象作为其状态一部分的容器，并更新该容器的状态:

function f(container) {
    container.obj = _ => console.log(
        'LOCAL object was replaced, how to replace from the outer scope?');
}

var c = {obj: fetch};    
f(c);
// ...use c.obj...

或

function f(container) {
    container[0] = _ => console.log(
        'LOCAL object was replaced, how to replace from the outer scope?');
}

var c = [fetch];    
f(c);
// ...use c[0]...