使用 JavaScript 读取本地文件

Question

So i have a file locally called "index.html" which i access using the "file://" protocol. (So not the "http://" protocol). I need to access a file "data.txt" in the same directory which is continuously changed by a seperate program, but since i'm using the file protocol the access to the file is denied for security reasons.

What could i do to read the local file? I thought of running a local server using XAMPP or WAMP but i'd rather not use any extra programs.

EDIT: I cannot use an input file, since it should work without any user interaction.

Answer 1

You may do it via the File API - https://www.w3.org/TR/file-upload/

The example below filters out images from the user's selection, calls reader.readAsDataURL() on the file, and renders a thumbnail by setting the 'src' attribute to a data URL.

 <style> .thumb { height: 75px; border: 1px solid #000; margin: 10px 5px 0 0; } </style> <input type="file" id="files" name="files[]" multiple /> <output id="list"></output> <script> function handleFileSelect(evt) { var files = evt.target.files; // FileList object // Loop through the FileList and render image files as thumbnails. for (var i = 0, f; f = files[i]; i++) { // Only process image files. if (!f.type.match('image.*')) { continue; } var reader = new FileReader(); // Closure to capture the file information. reader.onload = (function(theFile) { return function(e) { // Render thumbnail. var span = document.createElement('span'); span.innerHTML = ['<img class="thumb" src="', e.target.result, '" title="', escape(theFile.name), '"/>'].join(''); document.getElementById('list').insertBefore(span, null); }; })(f); // Read in the image file as a data URL. reader.readAsDataURL(f); } } document.getElementById('files').addEventListener('change', handleFileSelect, false); </script>