How to read local text files in html

HTML itself cannot directly read local files, but it can be solved by the following methods: Using the FileReader API: Use the readAsText() method of the FileReader API to read the text file content. Using XMLHttpRequest: Use XMLHttpRequest (XHR) to send an HTTP request to the server to read a local file. Using Fetch API: Use Fetch API to send HTTP requests, similar to XMLHttpRequest, but providing a more modern way.

How to read local text files in HTML

HTML itself cannot directly access the local file system. However, we can solve this problem by the following methods:

Use the FileReader API

The FileReader API provides the readAsText() method, which can be used to read Get text file content:

<code class="html"><input type="file" id="file-input">

<script>
  const fileInput = document.getElementById('file-input');
  fileInput.addEventListener('change', (e) => {
    const file = e.target.files[0];
    const reader = new FileReader();
    reader.onload = (e) => {
      const text = e.target.result;
      // 使用 text
    };
    reader.readAsText(file);
  });
</script></code>

Using XMLHttpRequest

XMLHttpRequest (XHR) is an API that interacts with the server through HTTP requests. We can use this to read local files:

<code class="html"><script>
  const request = new XMLHttpRequest();
  request.open('GET', 'local-file.txt');
  request.onload = () => {
    const text = request.responseText;
    // 使用 text
  };
  request.send();
</script></code>

Using Fetch API

Fetch API is an alternative to XHR and provides a more modern way to handle HTTP Request:

<code class="html"><script>
  fetch('local-file.txt')
  .then(response => response.text())
  .then(text => {
    // 使用 text
  })
  .catch(error => {
    // 处理错误
  });
</script></code>

NOTE: Due to security reasons, these methods can only read text files from the same source (domain, protocol and port).

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