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PODetecting a file's content-type when using JavaScript's FileReader interface
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copied!<p>I've been setting up an import script for plain-text files in a web application.</p> <p>My script is as follows:</p> <pre><code>function dataImport(files) { confirm("Are you sure you want to import the selected file? This will overwrite any data that is currently saved in the application workspace."); for (i = 0; i < files.length; i++) { file = files[i] console.log(file) var reader = new FileReader() ret = [] reader.onload = function(e) { window.localStorage.setItem("ApplicationData", e.target.result); } reader.onerror = function(stuff) { console.log("error", stuff) console.log (stuff.getMessage()) } reader.readAsText(file) } } </code></pre> <p>It's essentially a modification of that posed on <a href="https://stackoverflow.com/questions/4100927/chrome-filereader">this question</a>.</p> <p>However, at the moment the user can technically attempt to import any file. As it's designed for plain-text files, problems can arise if a different type of file is imported.</p> <p>I've noticed in the console that the browser detects the content-type of the file being imported. Here's an example.</p> <pre><code>fileName: "ideas.txt" fileSize: 377 name: "ideas.txt" size: 377 type: "text/plain" webkitRelativePath: "" </code></pre> <p>Is it possible, then, to set up an argument where the script detects the content-type of the file, and if it isn't one of a number of specified suitable content-types, have the script refuse to import it?</p> <p>Thanks in advance for any advice.</p>

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