Answers for "usecontext example"

useRef

/*
	A common use case is to access a child imperatively: 
*/

function TextInputWithFocusButton() {
  const inputEl = useRef(null);
  const onButtonClick = () => {
    // `current` points to the mounted text input element
    inputEl.current.focus();
  };
  return (
    <>
      <input ref={inputEl} type="text" />
      <button onClick={onButtonClick}>Focus the input</button>
    </>
  );
}

react usecontext examples

import React from "react";
import ReactDOM from "react-dom";

// Create a Context
const NumberContext = React.createContext();
// It returns an object with 2 values:
// { Provider, Consumer }

function App() {
  // Use the Provider to make a value available to all
  // children and grandchildren
  return (
    <NumberContext.Provider value={42}>
      <div>
        <Display />
      </div>
    </NumberContext.Provider>
  );
}

function Display() {
  // Use the Consumer to grab the value from context
  // Notice this component didn't get any props!
  return (
    <NumberContext.Consumer>
      {value => <div>The answer is {value}.</div>}
    </NumberContext.Consumer>
  );
}

ReactDOM.render(<App />, document.querySelector("#root"));



//now with useContext the same page look like this
// import useContext (or we could write React.useContext)
import React, { useContext } from 'react';

// ...

function Display() {
  const value = useContext(NumberContext);
  return <div>The answer is {value}.</div>;
}

useContext

const value = useContext(MyContext);