How can I use a function from another file in react?

Question

I would like to create a file (function.js) for a function that does this:

let i = 0;
    if (this === that) {
        i = 0;
    } else {
       i = 1;
    }

I would then like to add it to (this.js)

import function from "./function";
class Example extends Component {
    state = {
        test
    };
    render() {
        function()
    return (
        <div>
            <h1>{this.state.test.sample[i].name}</h1>
        </div>

Answer 1

You can do something like:

function.js

const doSomething = function() {
let i = 0;
    if (this === that) {
        i = 0;
    } else {
       i = 1;
    }

}

export default doSomething;

App.js (for example):

import doSomething from "./function";

class Example extends Component {
    state = {
        test
    };
    render() {
        doSomething()
    return (
        <div>
            <h1>{this.state.test.sample[i].name}</h1>
        </div>
     )