在Reacjs中导入另一个（帮助器）类

Question

I want to write a helper class for like:

export default class A {
  constructor() {
    console.log(1);
  }
  test() {
    console.log(2);
  }
}

that I can use it in my component:

import React, { Component } from "react";
import A from "./service/socket";

class Test extends Component {
  state = {
    counter: 0
  };

  componentDidMount = () => {
    A.test();
  };
}

how can I do that?

Answer 1

test is a method on an instance of A . If you just want to create a collection of helper functions and don't actually need a class , export the functions directly from the module:

// ./service/socket
export function test() {
  console.log(2);
}

// somefile.js
import {test} from './service/socket';
test();

---

If you really need a class, you'd have to create an instance first, eg

import React, { Component } from "react";
import A from "./service/socket";

const instanceA = new A();

class Test extends Component {
  state = {
    counter: 0
  };

  componentDidMount = () => {
    instanceA.test();
  };
}

But you shouldn't use classes as bags of methods.