How to pass data in react js inside a file

What about using a state :

With the React hook useState :

import React, { useState } from React;

then

const [selectedKeys, setSelectedKeys] = useState([]);

then

function handleClick(key) {
  localStorage.setItem('my-item', key);
  let newKeys = selectedKeys.slice(0); // you may need to clone the array
  newKeys.push(key);
  setSelectedKeys(newKeys); // or push it into an array if there is many.
}

your Menu component would then look like :

<Menu
 mode="inline"
 selectedKeys={selectedKeys}   
 openKeys={openKeys}
 onOpenChange={onOpenChange}
 style={{ width: 500px}}
 onClick={() => handleClick(e.key)}>

All together :

import React, { useState } from React;

const App = () => {
  const [selectedKeys, setSelectedKeys] = useState([]);

  const handleClick = (key) => {
    localStorage.setItem('my-item', key);
    let newKeys = selectedKeys.slice(0); // you may need to clone the array
    newKeys.push(key);
    setSelectedKeys(newKeys); // or push it into an array if there is many.
  }

  return {
    <Menu
     mode="inline"
     selectedKeys={selectedKeys}   
     openKeys={openKeys}
     onOpenChange={onOpenChange}
     style={{ width: 500px}}
     onClick={() => handleClick(e.key)}>
  }
}

Make it a class component and in the state make an attribute of selected key and in the handleClick do set the state and assign the selectedKey value from the state in the Menu tag. Thats the proper way of doing it.

import React, { Component } from 'react';

class App extends Component {
  constructor(props){
    super(props);
    this.state = {
        selectedKey: null
    };
  }
  handleClick = (e) => {
    console.log('click ', e);
    this.setState({
       selectedKey: e.key         
    });
    localStorage.setItem('my-item', e.key);
    console.log(localStorage.getItem('my-item'));
  }
  render () {
    return (
      <div>
        <Menu
          selectedKeys={this.state.selectedKey}   
          style={{ width: 500px}}
          onClick={handleClick}
        >
        ...another code
  }
}

Use an arrow function:

onClick={() => handleClick(e.key)}

In your code:

  handleClick = key => {
    console.log("the key is:", key);
    localStorage.setItem('my-item', key);
    console.log(localStorage.getItem('my-item'))
  }

  <Menu
    selectedKeys={e.key}   
    style={{ width: 500px}}
    onClick={() => handleClick(e.key)}>