Javascript Regex: Bolding needles in a haystack


Related (but not the same):

Javascript Regex: How to bold specific words with regex?

Given a needle and a haystack… I want to put bold tags around the needle. So what regex expression would I use with replace()? I want SPACE to be the delimeter and I want the search to be case insensitive and I want special characters (such as @!#.()) to be ignored in the search

so say the needle is "cow" and the haystack is

cows, at, milk some COWS!

would turn into

<b>cows</b>, at, milk some <b>COWS</b>!

also keywords should be able to have spaces in it so if the keyword is "who is mgmt"…

great band. who. is. mgmt btw?

would turn into

great band. <b>who. is. mgmt</b> btw?

I've got this currently:

function updateHaystack(input, needle) {
    return input.replace(new RegExp('(^|\\s)(' + needle + ')(\\s|$)','ig'), '$1<b>$2</b>$3');

unfortunately it doesn't bold words that are concatenated with a special char… eg. !cow does not turn into !<b>cow</b>

Thank you

Best Solution

It sounds like \b should do what you want. It's a zero-width match of "word boundaries".

function updateHaystack(input, needle) {
    return input.replace(new RegExp('\\b(' + needle + ')\\b','ig'), '<b>$1</b>');