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I'm trying to comment regular expressions in JavaScript.
There seems to be many resources on how to remove comments from code using regex, but not actually how to comment regular expressions in JavaScript so they are easier to understand.
299
$ means "Match the end of the string" (the position after the last character in the string). Both are called anchors and ensure that the entire string is matched instead of just a substring.
\n. Matches a newline character. \r. Matches a carriage return character.
The $ number language element includes the last substring matched by the number capturing group in the replacement string, where number is the index of the capturing group. For example, the replacement pattern $1 indicates that the matched substring is to be replaced by the first captured group.
The curly brackets are used to match exactly n instances of the proceeding character or pattern. For example, "/x{2}/" matches "xx".
Unfortunately, JavaScript doesn't have a verbose mode for regular expression literals like some other langauges do. You may find this interesting, though.
In lieu of any external libraries, your best bet is just to use a normal string and comment that:
var r = new RegExp(
'(' + //start capture
'[0-9]+' + // match digit
')' //end capture
);
r.test('9'); //true
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