Please un-deprecate url.resolve

[evert]

What steps will reproduce the bug?

We use url.resolve a LOT. It's a great function that also inspired me to write a PHP version with 8 million downloads =)

I recently discovered that url.resolve() was marked as deprecated, and that users should use URL instead.

Aside from the fact that WhatWG URL is not a real RFC3986 uri, there's also a a very simple feature missing. We use url.resolve all the time to do things like this:

const newUrl = url.resolve(
  '/base'
  '?foo=bar'
);

The URL object does not let us work with relative urls:

> new URL('?foo=bar', '/bar');
Uncaught TypeError [ERR_INVALID_URL]: Invalid URL: /bar
    at onParseError (internal/url.js:259:9)
    at new URL (internal/url.js:335:5)
    at new URL (internal/url.js:332:22)
    at REPL11:1:1
    at Script.runInThisContext (vm.js:133:18)
    at REPLServer.defaultEval (repl.js:484:29)
    at bound (domain.js:413:15)
    at REPLServer.runBound [as eval] (domain.js:424:12)
    at REPLServer.onLine (repl.js:817:10)
    at REPLServer.emit (events.js:327:22) {
  input: '/bar',
  code: 'ERR_INVALID_URL'

[jasnell]

The challenge is not that URL does not support relative URLs, it's that it is designed to work for more than just HTTP URLs and needs to know the protocol to properly resolve the URL (since different URL protocol schemes use different resolve and serialization algorithms). You can achieve what you're looking for by appending a prefix to the /bar, then ignoring that prefix in the result:

const { pathname, search } = new URL('?foo=bar', 'http://example/bar');
console.log(pathname + search);  // Outputs: /bar?foo=bar

[evert]

Interesting, that makes sense! It's just tricky to handle. I work a lot on HATEOAS-style systems, where people just generally want to use relative urls.

What I need is some way for the origin to be preserved if it was supplied in any of the 2 components, but removed if both were relative. I could solve this by supplying a domain that will never be registered, but it's a bit clumsy.

I do appreciate the reasoning here though, so feel free to close,

[jasnell]

The example.org/example.com domains are safe to use. They are officially registered by IANA/IETF and used for examples in IETF standards.

What I need is some way for the origin to be preserved if it was supplied in any of the 2 components, but removed if both were relative.

The way to handle this is to use two resolves:

function resolve(path, base) {
  const baseUrl = new URL(base, 'http://example.com');
  const { pathname, search } = new URL(path, baseUrl);
  return pathname + search;
}

resolve('?foo=bar', '/bar');
resolve('?foo=bar', 'https://example.org/bar');

[aduh95]

PR to add the suggested replacement function: #37501