Warning: This synthetic event is reused for performance reasons happening with <input type=“checkbox” />

Question

I\'ve been working on a simple react-redux todo example for a class and I came across several warning messages that show in the console everytime I check and uncheck a checkbox

Answer 1

This happened because the event implicitly passed to onItemClick is used in an asynchronous context.
As Andre Lemay said, you should assign your needs to local variables and reference them.

In my case, I had this code:

handleInput = e => { // <-- e = synthetic event
  this.setState(state => ({ // <-- asynchronous call
    data: {
      ...state.data,
      [e.target.name]: e.target.value // <-- this was causing the warnings (e.target is in an asynchronous context)
    }
  }));
};

Then I changed it to:

handleInput = e => {
  const { name, value } = e.target; // <-- moved outside asynchronous context

  this.setState(state => ({
    data: {
      ...state.data,
      [name]: value
    }
  }));
};