Javascript：为什么我的代码没有任何警报？

发布于 2024-08-10 13:59:12 字数 915 浏览 3 评论 0原文

我编写了以下内容：

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");

但是，当它应该发出警报 "{score:33,index: 0},{得分:0,索引:1}"。

谁能告诉我为什么会这样？

非常感谢

原文

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

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梦里°也失望 2024-08-17 13:59:12

您将 percentageScores 设置为一个数字。然后，您尝试迭代其 length 属性，当您执行 percentageScores.length 时，该属性会给出 undefined，因此 for 循环永远不会迭代。然后，您使用一个空数组发出警报，其 toString 会生成空字符串。

你可能想要这个：

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;
};

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;
};

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