Find a value between two strings using regex

[Aidan]

(originally posted under Now Platform)

I'm looking to parse a script field to find any messages that have been referenced in gs.getMessage() calls.  The following regex works fine in any online test website but not in ServiceNow;

(?<=getMessage\(\").*?(?=\")

Here's the code I'm trying to use;

var regex = new RegExp(/(?<=getMessage\(\").*?(?=\")/g);

which returns the following error when tested/exec'd

Evaluator: com.glide.script.RhinoEcmaError: Invalid quantifier ?
   Line(0) column(0)

Looks to me like the Positive Lookbehind is failing, but not sure of an alternative.

[Brian Lancaster]

I check your reg expression at https://www.regextester.com/ and I get a message there the lookbehind is not supported in Javascript.

[Aidan]

The message I was getting was that it wasn't supported in all browsers.  Are there any alternatives then?

[Brian Lancaster]

I'm not sure I follow you requirements.  Can you give more details?

[Aidan]

Sure, essentially I'm looking to scan through the script field for various records to see what custom messages  are being referenced.  So if there is a script such as the following;

/* display message */
alert(getMessage("Custom text message"));

/* get message and store */
var msg = getMessage("Store custom message");

I want to have the following returned;

Custom text message
Store custom message