Question

I’m trying to match the text “foo” between the two brackets in this following statement:

Expected [foo] but Recieved [__]

I’m then trying to replace the text with “…”. When I run the following code I get an invalid grouping error in JavaScript. When I run the expression in Regexr it works the way I expect it to.

var text = $("#assertion").html().replace( /(?<=Expected \[).*(?=\] )/,"...");

http://jsfiddle.net/bittersweetryan/VcraW/

Answer 1

Javascript regexes don’t understand lookbacks (the ?<=). You need to match the Expected [ part explicitely:

replace(/(Expected \[)[^\]]*/, "$1...")

The $1 is to avoid retyping the “Expected [” part and I changed the rest of the regex a bit to avoid greedy matching with .*

http://jsfiddle.net/VcraW/2/