JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.js"></script>
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.2/themes/ui-lightness/jquery-ui.css">

JavaScript

var string = "jak har en mamma";

string = string.replace(/(jak)|(mamma)/g,function(str,p1,p2) {
        if(p1) return 'du';
        if(p2) return 'pappa';
    });

alert(string);