如何将内置Javascript函数编码为递归函数（使用全局变量）

Question

我是JavaScript的新手，我被困在一个string.replace程序，需要使用递归函数和全局变量。目的是用另一个单词/短语（sub_key）替换单词/短语（sub_value）的任何实例，然后用sub_value填充句子的末尾。

这是我的基本代码：

function Obscure(sub_key, sub_value, sentence) {
  var obscuredSentence = sentence.replace(sub_key, sub_value);
  var obscuredSentence = sub_value + " " + obscuredSentence + " " + sub_value;
  return obscuredSentence;
}

console.log(Obscure("the", "the goat", "I want the money")

    //--> "the goat I want the goat money the goat" );

但是，我需要编写一个运行两次（并且只有两次）的递归函数，以便在sub_key还包含sub_value（例如“the goat”）的情况下继续用sub_value替换sub_key。我的最后一句应该是“山羊我要山羊山羊钱山羊”。

我尝试了这段代码，但它溢出了堆栈（ha）：

function Obscure(sub_key, sub_value, sentence) {
  var obscuredSentence = sentence.replace(sub_key, sub_value);

  for (var count = 1; count < 2; count++) {
    return Obscure(sub_key, sub_value, sentence);
  }

  var obscuredSentence = sub_value + " " + obscuredSentence + " " + sub_value;
  return obscuredSentence;
}

console.log(Obscure("the", "the goat", "I want the money"));
//"RangeError: Maximum call stack size exceeded (line 2 in function Obscure)"

非常感谢任何帮助/建议。非常感谢。

Answer 1

我对您的代码进行了一些小改动，如果您只想执行两次，它应该可以解决您的问题。

var count = 1;

function Obscure(sub_key, sub_value, sentence) {
  var obscuredSentence = sentence.replace(sub_key, sub_value);

  for (; count < 2;) {
    count++;
    return Obscure(sub_key, sub_value, obscuredSentence);
  }

  var obscuredSentence = sub_value + " " + obscuredSentence + " " + sub_value;
  return obscuredSentence;
}

console.log(Obscure("the", "the goat", "I want the money"));

Answer 2

for(不是递归的，它是迭代的。

你需要两个函数：一个带有递归调用的辅助函数，另一个只需要填充结尾并调用递归fn。就像是

function obscureInside(sub_key, sub_value, sentence, repetitions) {
  if (repetitions <= 0) {
    return sentence;
  }

  var sentenceAfterSingleRun = sentence.replace(sub_key, sub_value);
  return obscureInside(sub_key, sub_value, sentenceAfterSingleRun, repetitions - 1);

}

function obscure(sub_key, sub_value, sentence) {
  var obscuredSentence = obscureInside(sub_key, sub_value, sentence, 2);
  return sub_value + " " + obscuredSentence + " " + sub_value;
}

console.log(obscure("the", "the goat", "I want the money"));