Replace text (with question mark) using regex

Question

I want to replace a text which contains "?" character using regex.

var test = "{=countAreas?area=123}";

I want to replace it with:

"{=countAreas?area=123}X"

I tried below code but "?" character creates an issue since it's a part of regex's identifiers:

test.replace(new RegExp(arrMatch[i], 'g'), "" + arrMatch[i] + "X");