Given the string: the_number_10_is_important, I want to capture _10_ and exclude 10.
I essentially want to replace all underscores surrounding digits with brackets.
_\d+_ selects _10_ is my starting point. I'm trying to use lookaround or a non-capturing group eg. _(?:\d+)_
Just to close this then, with credit to The fourth bird
You have to use a capture group and repeat the digits
"the_number_10_is_important".replace(/_(\d+)_/g, "[$1]");
Here's my own version, but with sed which doesn't have proper support for \d:
sh$ echo "the_number_10_is_important_ but 10 should not be fooled by the real_0_ or the fake_1" | sed -E -e 's/_([0-9]+)_/[\1]/g'
the_number[10]is_important_ but 10 should not be fooled by the real[0] or the fake_1
You need to capture the number and give it back in the replacement, so you replace the whole _10_ part instead of just the underscores.
var s = "the_number_10_is_important";
var x = s.replace(/_(\d+)_/gm, "($1)");
console.log(x);
It is possible to do it your way too with lookaround, but it is somewhat more complicated.
var s = "the_number_10_is_important";
var x = s.replace(/_(?=\d+)/gm, "(").replace(/(?<=\d+)_/gm, ")");
console.log(x);
.replace(/_(\d+)_/g, "($1)")?"the_number_10_is_important".replace(/_(\d+)_/g, "[$1]");replaceseems to work fine in this case.