If you use the 'x' flag of XRegExp, it is unclear how to add the literal '#' to the search.
The documentation does not appear to yield any illumination.
For example:
> XRegExp("the # hey",'x').toString()
'/the(?:)/'
This is as expected - everything after '#' is a comment and ignored.
The apparent solution, not ignoring the # and following contents on that line, would usually be (based on my limited experience) leading with an escape modifier, eg \\:
> XRegExp("the \# hey",'x').toString()
'/the(?:)/'
or
> XRegExp("the \\# hey",'x').toString()
'/the(?:)\\#(?:)hey/'
Unfortunately neither works as expected, the prior for obvious reasons, and the latter yields:
> XRegExp("the \\# hey",'x').xtest("the # hey")
false
or even in the more pernicious case that we must modify input data:
> XRegExp("the \\# hey",'x').xtest("the \\# hey")
false
The alternative canonical escaping would be using a double-hash (##), but that does not work either:
> XRegExp("the ## hey",'x').toString()
'/the(?:)/'
So the question becomes, how can one add a # literal to an XRegExp expression that uses the 'x' flag? I'm stumped.
I found the answer and please note that my tests above would not work because the spaces should be replaced by \\s+.
The answer seems to be to use [#] e.g.
> XRegExp("the\\s+[#]\\s+hey",'x').xtest("the # hey")
true