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HTML

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HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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Adding Classes

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About the <head>

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CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

All packages are different, so refer to their docs for how they work.

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HTML 

              
                <div class="wrapper">
  <input type="date" class="input-date">
  <button class="btn">表示する</button>
  <p class="display"></p>
</div>
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CSS 

              
                .wrapper {
  text-align: center;
  margin-top: 60px;
}

.display {
  margin-top: 30px;
}
!

JS 

              
                //inputフォームを取得
const inputDate = document.querySelector('.input-date');
//ボタンを取得
const btn = document.querySelector('.btn');
//日付を表示するためのpタグを取得
const display = document.querySelector('.display');

//ボタンをクリックすると処理を実行
btn.addEventListener('click', () => {
  //日付を選択していないときは処理が終了
  if(!inputDate.value) {
    return;
  }
  
  
  //日付を取得
  const fullDate = new Date(inputDate.value);
  //年を取得
  const getYear = fullDate.getFullYear();
　//月を取得
  const getMonth = fullDate.getMonth() + 1;
　//日を取得
  const getDate = fullDate.getDate();
  
  // 日付を2024/1/1の形式にする
  const formattedDate = `${getYear}/${getMonth}/${getDate}`;
  
  //pタグに日付を代入
  display.innerText = '入力した日付:　' + formattedDate;
});
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999px

Console