场景：
A.js

 const demo = {
    a:1,
    b:2
 }

B.js

 const demo = {
    c:3,
    d:5
 }

index.js

import envs from "./env";
import localenvs from "./localEnv";

// 如何导出

如何在其他文件引入？？？：
test.vue

import {a,b,c,d} from 'index.js'

a.js

const demo = {
  a:1,
  b:2
}
export default demo

b.js

const demo = {
  c:2,
  d:4
}
export default demo

ab.js

import a from "./a"
import b from "./b"

export default {...a,...b}

test.vue

import {a,b,c,d} from "./ab"

index.js:

export * from 'a.js';
export * from 'b.js';