Lazy match Node regex over multiple lines - regex

Question

I'm trying to parse a bunch of javascript files and pull out certain objects. an example of the file would be:
import { foo } from "blah";
import { bar, baz } from "../module";
const myobject = {
name: NAME,
title: {
name: `${NAME}.title`,
defaultMessage: "title",
},
description: {
name: `${NAME}.description`,
defaultMessage: "description",
},
property: 'stringvalue',
};
const anotherObject = {
name: `${NAME}.other`,
defaultMessage: "other",
}
I need to pull out all the objects that have the property "defaultMessage". For the matcher I have:
/\{([\s\S]*?)defaultMessage([\s\S]*?)\}/g
This is matching anotherObject and myobject.description correctly, but for myobject.title it's getting everything from the first { before foo. e.g:
{ foo } from "blah";
import { bar, baz } from "../module";
const myobject = {
name: NAME,
title: {
name: `${NAME}.title`,
defaultMessage: "Main",
}
How can I get this to lazy match further so I only get:
{
name: `${NAME}.title`,
defaultMessage: "Main",
}
Update: I'll be using node to parse the javascript files, so I get access to negative look behinds, I tried the following with no luck:
(?<!\{[\s\S]+?)\{([\s\S]+?)defaultMessage([\s\S]*?)\}

Answer 1

I would not use this in any production code but this would work for your case:
([a-zA-Z]*?)(?:\s=|:)\s(\{(?:(?!([a-zA-Z]*?)(\s=|:)\s\{)[\s\S])*?defaultMessage(?:[\s\S]*?)\})
I added ([a-zA-Z]*?)(\s=|:)\s, so that we only capture the opening bracket if it is prefixed by xyZ = or `abC:'.
Also added a negative lookahead so that the pattern doesn't repeat itself:
(?!([a-zA-Z]*?)(\s=|:)\s\{)
Furthermore I added some non capturing groups in order to decrease regex group clutter if you intend to use this in some code. For example this regex captures:
title: {
name: `${NAME}.title`,
defaultMessage: "title",
}
With title as sub group 1
and:
{
name: `${NAME}.title`,
defaultMessage: "title",
}
As subgroup 2, you can approach subgroup 2 in order to get your desired capture.
Alternatively use:
(?=[a-zA-Z]*?)\{(?:(?!([a-zA-Z]*?)(\s=|:)\s\{)[\s\S])*?defaultMessage(?:[\s\S]*?)\}
To only capture:
{
name: `${NAME}.title`,
defaultMessage: "title",
}
With no subgroups