Apps Script findText() for Google Docs - regex

Question

I'm applying RegEx search to a Google Document text with some markdown code block ticks (```). Running the code below on my doc is returning a null result.
var codeBlockRegEx = '`{3}((?:.*?\s?)*?)`{3}'; // RegEx to find (lazily) all text between triple tick marks (/`/`/`), inclusive of whitespace such as carriage returns, tabs, newlines, etc.
var reWithCodeBlock = body.findText(codeBlockRegEx); // reWithCodeBlock evaluates to 'null'
I suspect that there's some element of regex in my code that is not supported by RE2, but the documentation has not shed light on this. Any ideas?

Answer 1

I received null as well- I was able to get the below to work using 3 ` surrounding the word test within a paragraph.
I did find this information:
findText method of objects of class Text in Apps Script, extending Google Docs. Documentation says “A subset of the JavaScript regular expression features are not fully supported, such as capture groups and mode modifiers.” In particular, it does not support lookarounds.
function findXtext() {
var body = DocumentApp.getActiveDocument().getBody();
var foundElement = body.findText("`{3}(test)`{3}");
while (foundElement != null) {
// Get the text object from the element
var foundText = foundElement.getElement().asText();
// Where in the element is the found text?
var start = foundElement.getStartOffset();
var end = foundElement.getEndOffsetInclusive();
// Set Bold
foundText.setBold(start, end, true);
// Change the background color to yellow
foundText.setBackgroundColor(start, end, "#FCFC00");
// Find the next match
foundElement = body.findText("`{3}(test)`{3}", foundElement);
}
}