<!DOCTYPE html>

<html lang="ja">

<head>

  <meta charset="UTF-8">

  <meta name="viewport" content="width=device-width, initial-scale=1.0">

  <title>JavaScript Practice</title>

  <style>

    .box{

      width: 100px;

      height: 100px;

      background: skyblue;

      cursor: pointer;

      transition: 1s;

      margin: 5px;

      text-align: center;

      line-height: 100px;

          }

    .circle{

      background: red;

      border-radius: 40%;

      transform: rotate(360deg);

          }

     body{

       display: flex;

       flex-wrap: wrap;

     }

  </style>

</head>

<body>

  <!-- <div class="box" id="target1"></div>

  <div class="box" id="target2"></div>

  <div class="box" id="target3"></div> -->

  <script>

    'use strict';

   

    for(let i = 0; i <  100; i++){

    const div = document.createElement('div');

    div.classList.add('box');

    div.textContent = i;

    div.addEventListener('click', () => {

      div.classList.toggle('circle');

    });

 

    document.body.appendChild(div);

 

    }

 

    // document.body.appendChild(div);

 

      // document.getElementById('target').

      // addEventListener('click', ()=>{

      // document.getElementById('target').classList.toggle('circle');

 

      // const target1 = document.getElementById('target1');      

      // const target2 = document.getElementById('target2');      

      // const target3 = document.getElementById('target3');      

      // target1.addEventListener('click', ()=>{

      //   target1.classList.toggle('circle');

      // });

 

      // target2.addEventListener('click', ()=>{

      //   target2.classList.toggle('circle');

      // });

 

      // target3.addEventListener('click', ()=>{

      //   target3.classList.toggle('circle');

      // });

  </script>

</body>

</html>