Javascript: Why is my code alerting to nothing?

Question

I've written the following:

var pages=["[www.facebook.com] Facebook is cool. ","[www.bbc.co.uk] British broadcasting corporation. "];

function findScoreC2(s){ 
  var scores=[];
  var percentageScores=[];
  var contentsArray=[];
  s=s.toLowerCase();
  for(i=0;i<pages.length; i++){
    contentsArray=pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "));
    var lowerCaseContents=(pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "))).toLowerCase();
    scores[i] =(lowerCaseContents.split(s)).length-1
  };

  percentageScores=(scores[i] / contentsArray[i].length) * 100;
  var finalArray=[];

  for(i=0;i<percentageScores.length;i++){
    finalArray.push("{score:"+percentageScores[i]+",index:"+i+"}")
  };
  alert(finalArray);
}


findScoreC2("facebook");

however, alert(finalArray) alerts to nothing (ie an alert box comes up but it says nothing) when it should alert "{score:33,index:0},{score:0,index:1}".

Could anyone enlighten me as to why this might be?

Thanks very much

Answer 1

You set percentageScores to a number. You then try to iterate up to its length property, which gives you undefined when you do percentageScores.length, so the for loop never iterates. You then alert with an empty array, whose toString produces the empty string.

You probably want this:

for(i=0;i<pages.length; i++){
    contentsArray=pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "));
    var lowerCaseContents=(pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "))).toLowerCase();
    scores[i] =(lowerCaseContents.split(s)).length-1
    percentageScores[i]=(scores[i] / contentsArray[i].length) * 100;
};