Javascript Regex: How to bold specific words with regex?

Question

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

Answer 1

Here is a regex to do what you're looking for:

(^|\s)(cows)(\s|$)

In JS, replacement is like so:

myString.replace(/(^|\s)(cows)(\s|$)/ig, '$1$2$3');

Wrapped up neatly in a reusable function:

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

var markup = document.getElementById('somediv').innerHTML;
var output = updateHaystack(markup, 'cows');
document.getElementById('somediv').innerHTML = output;