How to convert local file path to a file::?/ url safely in node.js?

Question

I have local file paths (in node.js) and I need to convert them into file:// urls.

I'm now looking at https://en.wikipedia.org/wiki/File_URI_scheme and I feel this must be a solved problem and somebody must have a snippet or npm module to do this.

But then I try to search npm for this but I get so much cruft it is not funny (file, url and path are a search hit in like every package ever :) Same with google and SO.

I can do this naïve approach

site = path.resolve(site);
if (path.sep === '\\') {
    site = site.split(path.sep).join('/');
}
if (!/^file:\/\//g.test(site)) {
    site = 'file:///' + site;
}

But I'm pretty sure that is not the way to go.

Solution 1

Use the file-url module.

npm install --save file-url

Usage:

var fileUrl = require('file-url');

fileUrl('unicorn.jpg');
//=> file:///Users/sindresorhus/dev/file-url/unicorn.jpg 

fileUrl('/Users/pony/pics/unicorn.jpg');
//=> file:///Users/pony/pics/unicorn.jpg

Also works in Windows. And the code is simple enough, in case you want to just take a snippet:

var path = require('path');

function fileUrl(str) {
    if (typeof str !== 'string') {
        throw new Error('Expected a string');
    }

    var pathName = path.resolve(str).replace(/\\/g, '/');

    // Windows drive letter must be prefixed with a slash
    if (pathName[0] !== '/') {
        pathName = '/' + pathName;
    }

    return encodeURI('file://' + pathName);
};

Solution 2

Node.js v10.12.0 just got two new methods to solve this issue:

const url = require('url');
url.fileURLToPath(url)
url.pathToFileURL(path)

Documentation

• https://nodejs.org/api/url.html#url_url_pathtofileurl_path
• https://nodejs.org/api/url.html#url_url_fileurltopath_url

Solution 3

I had a similar issue, but the solution ended up being to use the new WHATWG URL implementation:

const path = 'c:\\Users\\myname\\test.swf';
const u = new URL(`file:///${path}`).href;
// u = 'file:///c:/Users/myname/test.swf'

Comments

[Brian]

See this post for possible solution: stackoverflow.com/questions/18341808/…

[idmean]

Did you ever find a solution?

[Bartvds]

@wumm not really, I just use a naïve regexp based replacement like above commenter.

[Bartvds]

Thanks, this is what I was looking for back when I posted the question, I'll accept it for posterity.

[Mike Samuel]

This might break down if path contains any of ?, #, or %.

[Robert G. Schaffrath]

As of file-url version 4.0.0, the developer requires ESM, Node.js 12.0.0+ and no longer supports CommonJS (an error is thrown if you try to use require). Version 3.0.0 still works but 4.0.0 imposes these constraints that may not be acceptable to many developers. I am going to check out the url module and pathToFileURL() method.