I am trying to write a Regex for a Cypress test to intercept a call to the backend. I have two calls, both PUTs, that are made to endpoints that look like this:

Call 1: /api/{randomId} Call 2: /api/{randomId}/approval

I need a regex that matches the first but not the second, and a regex that matches the second but not the first.

The second regex is easy: . \/api\/. \/approval will match the second URL but not the first:

The first regex though is tough because everything I've tried so far matches both URLs. For example, . \/api\/. matches both URLs:

I'm not really familiar with regexes and have tried several options on regexr (like a negative lookahead so that if the random ID is followed by a / it shouldn't match) but nothing has worked so far.

Any suggestions would be greatly appreciated.

CodePudding user response：

With negative lookahead, you can do something like this:

\/api\/(?!. ?\/approval). 

Basically, put the thing you don't want (so, a bunch of chars followed by \approval) entirely in the lookahead.

CodePudding user response：

To test for the first URL you can test for just the random pattern, followed by end of string:

const input = [
  '/api/qwerty123',
  '/api/qwerty123/approval',
  'https://example.com/api/random99',
  'https://example.com/api/random99/approval',
];
const regex1 = /^.*\/api\/[^\/] $/;
const regex2 = /^.*\/api\/[^\/] \/approval$/;

input.forEach(str => {
  let m1 = regex1.test(str);
  let m2 = regex2.test(str);
  console.log(`${str}: regex1 ${m1}, regex2 ${m2}`);
});

Output:

/api/qwerty123: regex1 true, regex2 false
/api/qwerty123/approval: regex1 false, regex2 true
https://example.com/api/random99: regex1 true, regex2 false
https://example.com/api/random99/approval: regex1 false, regex2 true

Explanation of regex1:

• ^ -- anchor at start of string
• .* -- greedy scan
• \/api\/ -- literal /api/
• [^\/] -- 1 chars that are not /
• $ -- anchor at end of string

Explanation of regex2:

• ^.*\/api\/[^\/] -- same as regex, expect for trailing anchor
• \/approval -- literal /approval
• $ -- anchor at end of string