Remove everything before the first forward slash in the url

Question

I need to remove everything before the third forward using regex so that for example https://stackoverflow.com/questions/ask becomes /questions/ask I'm not the greatest when it comes to regular expressions so your help would be much appreciated.

This is what I have so far https://regex101.com/r/qQ2dE4/498

The code I currently have is but want to use regex:

url.substring(url.indexOf('\/') + 3)

`url.indexOf('\/') + 3` wouldn't remove everything before the third / anyway - and your regex101 is not in javascript mode either — Jaromanda X, Nov 04 '20 at 22:13
Try `s = s.replace(/^(?:[^\/]*\/){3}/, '/')` or check this: https://regex101.com/r/qQ2dE4/499 — anubhava, Nov 04 '20 at 22:18

Alireza · Answer 1 · 2020-11-04T22:39:32.300

1

Use this:

(?<=.*\/.*\/.*\/).+

Demo

Explanation:

(?<= - its positive look behind, in any position that's pattern inside it is find matching start from this position to forward.
.*\/.*\/.*\/ - it is used inside the positive look behind, it cause matching start after the position that behind that position is 3 forward slashes
.+ - match one or more of from anything

Edit: From @JaromandaX's comment, this can also be used (and honestly I think it more readable and simper):

(?<=(?:.*?\/){3}).+

edited Nov 04 '20 at 22:39

answered Nov 04 '20 at 22:14

Alireza

2,103
1
6
19

Please can you explain what the regex is doing? – nless Nov 04 '20 at 22:16
why not `(?<=(?:.*?\/){3}).+` – Jaromanda X Nov 04 '20 at 22:17
1

@nless I edited my answer and add an explanation, hope this can help you – Alireza Nov 04 '20 at 22:31
1

@JaromandaX Yes, it can be used as well – Alireza Nov 04 '20 at 22:33

score 0 · Accepted Answer · answered Nov 04 '20 at 22:36

I understand the questions asks for regex but the need is unclear - if all you need is the path name there are better tools in the toolbox (for anybody not working on a homework exercise).

const url = 'https://stackoverflow.com/questions/ask'
console.log(new URL(url).pathname)

Remove everything before the first forward slash in the url

2 Answers2