如何貼上檔案

Harry Theodoulou

將檔案貼到瀏覽器中，需要使用 HTMLElement 的 paste 事件。

使用 HTMLElement's paste 事件

首先，請在所需元素中新增 paste 事件的事件監聽器，通常是在 document 層級，因此不需要聚焦特定元素。接著，您可以使用 Clipboard API 存取 HTMLElement 的 paste 事件的 clipboardData 欄位，然後疊代 files 清單。根據貼上檔案的 MIME 類型，您可以決定是否要將檔案顯示在畫面上 (如圖片或影片)，或是將檔案的文字內容貼到 textarea 元素中 (如文字檔案)。

Browser Support

  • Chrome: 66.
  • Edge: 79.
  • Firefox: 63.
  • Safari: 13.1.

Source

document.addEventListener('paste', async (e) => {
  // Prevent the default behavior, so you can code your own logic.
  e.preventDefault();
  if (!e.clipboardData.files.length) {
    return;
  }
  // Iterate over all pasted files.
  Array.from(e.clipboardData.files).forEach(async (file) => {
    // Add more checks here for MIME types you're interested in,
    // such as `application/pdf`, `video/mp4`, etc.
    if (file.type.startsWith('image/')) {
      // For images, create an image and append it to the `body`.
      const img = document.createElement('img');
      const blob = URL.createObjectURL(file);
      img.src = blob;
      document.body.append(img);
    } else if (file.type.startsWith('text/')) {
      // For text files, read the contents and output it into a `textarea`.
      const textarea = document.createElement('textarea');
      textarea.value = await file.text();
      document.body.append(textarea);
    }
  });
});

延伸閱讀

示範

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>How to paste files</title>
  </head>
  <body>
    <h1>How to paste files</h1>
    <p>Hit <kbd>⌘</kbd> + <kbd>v</kbd> (for macOS) or <kbd>ctrl</kbd> + <kbd>v</kbd>
      (for other operating systems) to paste image or text file(s) anywhere in this page.
    </p>
  </body>
</html>

CSS


        html {
  box-sizing: border-box;
  font-family: system-ui, sans-serif;
  color-scheme: dark light;
}

*, *:before, *:after {
  box-sizing: inherit;
}

body {
  margin: 1rem;
}

img {
  height: auto;
  max-width: 100%;
  display: block;
}

JS


        document.addEventListener('paste', async (e) => {
  // Prevent the default behavior, so you can code your own logic.
  e.preventDefault();
  if (!e.clipboardData.files.length) {
    return;
  }
  // Iterate over all pasted files.
  Array.from(e.clipboardData.files).forEach(async (file) => {
    // Add more checks here for MIME types you're interested in,
    // such as `application/pdf`, `video/mp4`, etc.
    if (file.type.startsWith('image/')) {
      // For images, create an image and append it to the `body`.
      const img = document.createElement('img');
      const blob = URL.createObjectURL(file);
      img.src = blob;
      document.body.append(img);
    } else if (file.type.startsWith('text/')) {
      // For text files, read the contents and output it into a `textarea`.
      const textarea = document.createElement('textarea');
      textarea.value = await file.text();
      document.body.append(textarea);
    }
  });
});