在 Node.js 中获取没有扩展名的文件的 MIME 类型

Question

Given I have a file without extension appended to its name, ex: images/cat_photo

Is there a method in Node.js to extract MIME type of a given file? Module mime in this case does not work.

Answer 1

Yes, there is a module called mmmagic . It tries best to guess the MIME of a file by analysing its content.

The code will look like this (taken from example ):

var mmm = require('mmmagic'),
var magic = new mmm.Magic(mmm.MAGIC_MIME_TYPE);

magic.detectFile('node_modules/mmmagic/build/Release/magic.node', function(err, result) {
    if (err) throw err;
    console.log(result);
});

But keep in mind, that the guessing of a MIME type may not always lead to right answer.

Feel free to read up on types signatures on a wiki page .

Answer 2

Another possibility is to use exec or execSync function to run the 'file' command on Linux SO:

/**
 * Get the file mime type from path. No extension required.
 * @param filePath Path to the file
 */
function getMimeFromPath(filePath) {
    const execSync = require('child_process').execSync;
    const mimeType = execSync('file --mime-type -b "' + filePath + '"').toString();
    return mimeType.trim();
}

However is not the better solution since only works in Linux. For running this in Windows check this Superuser question: https://superuser.com/questions/272338/what-is-the-equivalent-to-the-linux-file-command-for-windows

Greetings.

Answer 3

You could simply use String.prototype.split() and then take the last element of the array which will be the type.

You can take the last element on the array using the pop method:

const mimeType = fileName.split('.').pop()

or

const type = mimeType.split('/')

then type[1] will have the extension