regular expression for [allchars]

Question

I am trying to match something like [allchar] with a regular expression and be able to pull it out and replace it with other content

Here is what I am trying

Answer 1

reg = new RegExp("\\[.*?\\]", "g");
x = "[abc123.;.] this is more content";
console.log(x.replace(reg, "[contentreplacedwith]"));

If you use RegExp constructor the there's no need to pass / delimiters and the options like g for global are a second argument.