Question

Basically, I need to be able to find certain words (by ‘word’ I mean a set of characters) in a string (case insensitive) and if they match, I need to insert a symbol after the first letter of that particular set of characters. I can’t use search replace, as that would not preserve the case.

Example:

Brown brownies are in an oven.

If the word I’m looking for is brown, and the character I want to insert is *, the result should be:

B*rown b*rownies are in an oven.

What is the best way to do so in JS?

Answer 1

function astAfterFirstLetter(words) {
  var re = new RegExp("\\b(?=" + words.join("|") + "\\b)(\\w)(\\w*)", "gi");
  return function (str) { return str.replace(re, "$1*$2"); };
}

astAfterFirstLetter(["brown", "cow"])("How now brown cow!")

produces

How now b*rown c*ow!