Reactjs: useCallback and React.memo fun - code - 1

sample.js

let _int_val = 0;
const IntValComp = React.memo(({initFunc}) => {
  const [value, setValue] = React.useState(-1);
 
  // expect to init value once only
  React.useEffect(
    () => {
      const val = _int_val++;
      if (_int_val >= 100000) _int_val = 0;
 
      setValue(val);
      initFunc(val);
    },
    [initFunc],
  );
 
  return <div>{`int value zero: ${value}`}</div>;
});
 
const ParentComp = () => {
  const [intVal, setIntVal] = React.useState();
  const updateValue = React.useCallback((v) => setIntVal(v), []);
  return (
    <div>
      <IntValComp initFunc={updateValue} />
    </div>
  );
};