Javascript：为什么我的代码什么都不提醒？

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;
};