如何使用条件和 React Hooks 设置随机初始状态？

Question

This example simulates a coin toss.
I would like to randomize the initial state of the coin. The first time the page is loaded it could show heads. The next time, tails. To do so, I am using a random number generated by the Math method and a conditional to determine the face of the coin based on the random number (even number shows heads, odd shows tails).
The value needs to be displayed upon the initial render.

I also want to store the value in state using React's Hooks to use later in my app. How can I set a randomized initial state value using hooks?

Here is the code that I am working with. It currently does not function and I'm not sure what I am doing incorrectly to achieve my goal:

import React, { useState } from 'react';
import './App.css';

function App() {

  const [coin, setCoin] = useState(randomizePlayer())

  const randomizePlayer = () => {
    let number = Math.floor(Math.random() * 10) + 1
    return (number % 2 === 0) ? setCoin('Heads') : setCoin('Tails')
  }

    return (
      <div className="App">
        The coin is showing {coin}
      </div>
    );
  }

export default App;

I'm brand new to the hooks API and am using this exercise to learn.

Any help is appreciated!

Answer 1

I would rewrite this code as follows:

const randomizePlayer = () => {
  const number = Math.floor(Math.random() * 10) + 1
  return (number % 2 === 0) ? 'Heads' : 'Tails'
}

function App() {
  const [coin, setCoin] = useState(randomizePlayer())

  return (
    <div className="App">
      The coin is showing {coin}
    </div>
  );
}

randomizePlayer does not need to call setState ; let it just return a value. useState can use that value as its initial state.

Also to clarify: useState gets called just once. If you want coin to have a different value, the way to do that with this setup is to remount the component (reload the page).

State hooks docs