Edit in JSFiddle

require([
    "dojo/query", 
    "dojo/string", 
    "dojo/NodeList-manipulate", 
    "dojo/domReady!"
], function(query, string){
    var employee = {
        "first": "Kevin",
        "last": "Armstrong",
        "title": "Designer"
    };
    var template = "${first} ${last} is a great ${title}.";
    query("#out").html(string.substitute(template, employee, function(str){
	    return str.toLowerCase() == "designer" ? "<span class='special'>"+str+"</span>": str;
	}));
});

<div id="out"></div>

strong { font-weight: bold; text-decoration: underline; }
.special { font-weight: bold; color: #0099CC; }