regex returns 'Cannot read property '0' of null' in match()

Asked May 26 '20 at 12:17

Active May 26 '20 at 12:19

Viewed 13 times

This is the string i'm working with 8 August 1994 (age 25 years) I've been trying to match the 25 using

(?<=age ).*?(?= years),

but it returns
Evaluation failed: TypeError: Cannot read property '0' of null

It matches fine on regex101.com https://regex101.com/r/P5JYKx/2, so I don't understand the issue?

code

string.match(/(?<=age ).*?(?= years)/)

I'm using javascript regex.

edited May 26 '20 at 12:19

asked May 26 '20 at 12:17

srb633

Okay, just did that. – srb633 May 26 '20 at 12:20
2

@Nick Node.js supports lookbehinds. srb633, are you using the latest Node.js version? – Wiktor Stribiżew May 26 '20 at 12:21
Okay interesting, didn't know. I'm evaluating a page using headless chrome. That's probably why. – srb633 May 26 '20 at 12:21
Are you sure `string` is actually what you think it is? – Wiktor Stribiżew May 26 '20 at 12:22
The `string.match()` is contained inside an if statement which can only be accessed if the string is what I need it to be. So yes it's the correct variable. – srb633 May 26 '20 at 12:23
Let's assume it's because i'm using headless chrome, what alternative expression could I use for this task? – srb633 May 26 '20 at 12:24
1

Just use good old capturing groups, `string.match(/age\s+(.*?)\s+years/)[1]` – Wiktor Stribiżew May 26 '20 at 12:25
Haha alright sweet thank you. Feel free to write up a reply, seems that the issue has come down to headless chrome not supporting lookbehinds rather then the regex it self. – srb633 May 26 '20 at 12:28
1

See [my answer](https://stackoverflow.com/a/40782646/3832970). – Wiktor Stribiżew May 26 '20 at 12:29
Great thank you @WiktorStribiżew – srb633 May 26 '20 at 12:30

0 Answers0