Can I use require(“path”).join to safely concatena

Question

Is this safe to use require("path").join to concatenate urls, for example:

require("path").join("http://example.com", "ok"); 
//returns 'http://example.com/ok'

require("path").join("http://example.com/", "ok"); 
//returns 'http://example.com/ok'

If not, what way would you suggest for doing this without writing code full of ifs.

Answer 1

No. path.join() will return incorrect values when used with URLs.

It sounds like you want url.resolve. From the Node docs:

url.resolve('/one/two/three', 'four')         // '/one/two/four'
url.resolve('http://example.com/', '/one')    // 'http://example.com/one'
url.resolve('http://example.com/one', '/two') // 'http://example.com/two'

---

Edit: As Andreas correctly points out in a comment, url.resolve would only help if the problem is as simple as the example. url.parse also applies to this question because it returns consistently and predictably formatted fields via the URL object that reduces the need for "code full of ifs".

Answer 2

If you use Angular, you can use Location:

import { Location } from '@angular/common';
// ...
Location.joinWithSlash('beginning', 'end');

Works only on 2 arguments though, so you have to chain calls or write a helper function to do that if needed.

Answer 3

When I tried PATH for concatenating url parts I run into problems. PATH.join stripes '//' down to '/' and this way invalidates an absolute url (eg. http://... -> http:/...). For me a quick fix was:

baseurl.replace(/\/$/,"") + '/' + path.replace(/^\//,"") )

or with the solution posted by Colonel Panic:

[pathA.replace(/^\/|\/$/g,""),pathB.replace(/^\/|\/$/g,"")].join("/")

Answer 4

Axios has a helper function that can combine URLs.

function combineURLs(baseURL, relativeURL) {
  return relativeURL
    ? baseURL.replace(/\/+$/, '') + '/' + relativeURL.replace(/^\/+/, '')
    : baseURL;
}

Source: https://github.com/axios/axios/blob/fe7d09bb08fa1c0e414956b7fc760c80459b0a43/lib/helpers/combineURLs.js

Answer 5

No! On Windows path.join will join with backslashes. HTTP urls are always forward slashes.

How about

> ["posts", "2013"].join("/")
'posts/2013'

Answer 6

We do it like this:

var _ = require('lodash');

function urlJoin(a, b) {
  return _.trimEnd(a, '/') + '/' + _.trimStart(b, '/');
}