two_headlines_demo.js

var sentence1 = "Yemeni Government Collapses as President and Prime Minister Resign";
var sentence2 = "Diversity in play as Sundance Film Festival kicks off in Park City";

var tags1 = Tools.tagPos(sentence1);
var tags2 = Tools.tagPos(sentence2);

function findProperNounPhrase(tags){
	var previousTag = "";
	var properNounPhrase = "";
	for(var i = 0; i < tags.length; i++){
		if(tags[i].pos == "NNP" || tags[i].pos == "JJ"){
	      if(previousTag == "NNP" || previousTag == "JJ"){
	        properNounPhrase +=  " " + tags[i].word;
	      } else {
	        properNounPhrase = tags[i].word;
	      }
	    } else {
	    	if(properNounPhrase.length > 0){
	        	break;
	        }
	    }
	  previousTag = tags[i].pos;
	}

  	return properNounPhrase;
}

var pn1 = findProperNounPhrase(tags1);
var pn2 = findProperNounPhrase(tags2);

var newSentence = sentence1.replace(pn1, pn2);
console.log(newSentence);