Question

I want to take a string and remove all occurrences of characters within square brackets:

[foo], [foo123bar], and [123bar] should be removed

But I want to keep intact any brackets consisting of only numbers:

[1] and [123] should remain

I’ve tried a couple of things, to no avail:

text = text.replace(/\[^[0-9+]\]/gi, "");

text = text.replace(/\[^[\d]\]/gi, "");

Answer 1

The tool you’re looking for is negative lookahead. Here’s how you would use it:

text = text.replace(/\[(?!\d+\])[^\[\]]+\]/g, "");

After \[ locates an opening bracket, the lookahead, (?!\d+\]) asserts that the brackets do not contain only digits.

Then, [^\[\]]+ matches anything that’s not square brackets, ensuring (for example) that you don’t accidentally match “nested” brackets, like [[123]].

Finally, \] matches the closing bracket.