Question

我有工作。不幸的是我卡住了。你可以帮帮我吗。项目：

询问用户分析的句子。询问您希望用户使用哪些字母来计算块。计算字母在句子中出现的次数。弹出窗口然后键入以下句子：＆＃34;在该句中出现字母X乘Y.＆＃34; 必须使用功能！我写这个：

＆＃13;

function bernardTheLetterCounter() {
  var sentence = prompt("Please type in the phrase to be examined");
  var letter = prompt("Please enter the letters were looking for.");

  for (i = 0; i <= sentence.length; i++) {
    if (sentence.charAt(i) == letter) {
      alert("The letter " + letter + " occurs " + sentence.charAt(i) + " times in this sentence.")
    }
  }
  return;
}


bernardTheLetterCounter();

＆＃13;

Answer 1

您必须完成计数（循环内部），然后在循环完成后打印结果。像这样：

function bernardTheLetterCounter() {
  var sentence = prompt("Please type in the phrase to be examined");
  var letter = prompt("Please enter the letters were looking for.");

  var count = 0; // the counter (initialized to 0)
  // use var i instead of i (to make i local not global: this is just an advice)
  for (var i = 0; i <= sentence.length; i++) {
    if (sentence.charAt(i) == letter) { // if it is THE LETTER
      count++; // increment the counter (add 1 to counter)
    }
  }
  alert("The letter " + letter + " occurs " + count + " times in this sentence."); // use counter to print the result after the counting is done
  // the return here has no meaning
}


bernardTheLetterCounter();

你所做的就是每次找到信件时都会打印一条信息（这对用户来说很难看，特别是如果这封信的数量很大）。

Answer 2

此示例中的功能可以重复使用和测试。（ps。for-loop不是解决问题的有效方法）。

＆＃13;

var sentence = prompt("Please type in the phrase to be examined:");
var letter = prompt("Please enter the letter you are looking for:");

function countLettersInString(source, letterToFind) {
  return source
    .split('')
    .filter(function(letter) { return letter === letterToFind; })
    .length;
}

console.log([
  'letter', letter,
  'was found', countLettersInString(sentence, letter),
  'times.'
].join(' '));

＆＃13;

for js with starter for starter

2 个答案: