expected assignment or function call: no-unused-expressions ReactJS

Question

class Game extends Component 
{
  constructor() 
  {
    super()
    this.state = {
      speed: 0
    }
    //firebaseInit()
  }
  render()
  {
    return 
    (
           


        

Answer 1

The error - "Expected an assignment or function call and instead saw an expression no-unused-expressions" comes when we use curly braces i.e {} to return an object literal expression. In such case we can fix it with 2 options

1. Use the parentheses i.e ()
2. Use return statement with curly braces i.e {}

Example :

const items = ["Test1", "Test2", "Test3", "Test4"];
console.log(articles.map(item => { `this is ${item}` })); // wrong
console.log(items.map(item => (`this is ${item}`))); // Option1
console.log(items.map(item => { return `this is ${item}` })); // Option2

Answer 2

In my case, I got the error on the setState line:

increment(){
  this.setState(state => {
    count: state.count + 1
  });
}

I changed it to this, now it works

increment(){
  this.setState(state => {
    const count = state.count + 1

    return {
      count
    };
  });
}