Question

I need to get the javascript replace() function to replace every instance of a [b] or [/b] with <b> or </b>. I tried this with the global tag but it doesn’t work and comes out oddly:

document.write(str.replace(/[b]/g,'<b>').replace(/[/b]/g,'</b>'));

results in the output being:

[<>]<>la<>la[<>][<>]<>la<>la[<>] 

I also tried changing the first part to:

  document.write(str.replace(/[[b]]/g,'<b>').replace(/[[/b]]/g,'</b>'));

which kind of works, but there’s odd ]s everywhere… like so:

[blabla[/[blabla[/

I know there’s probably something obvious I’m missing here… But I can’t find it… any help and I will love you forever XD

Answer 1

[, ] and / are special RegExp characters.

• [a] means: Match any a character. [abcd] means: Match one character, which is one of a, b, c, d. [a-z] means: Match any letter.
• / is used to mark the beginning and end of a RegExp.

To use the literal characters, they have to be escaped.

str.replace(/\[b\]/g,'<b>').replace(/\[\/b\]/g,'</b>')

Note that both Regular expressions can be merged, using a backreference:

str.replace(/\[(\/?)b\]/g,'<$1b>')
// Replaces [b] with <b>, [/b] with </b>