函数式如何嵌套循环

问题描述

我正在学习函数式编程，完全摆脱 code> 或和一个合适的字符串函数：

  function isIsogram （string）{
 string = string.toLowerCase（）; //不区分大小写
 return string.split（''）。every（function（character，index）{
 return！string.includes（character，index + 1）; 
}）; 
 
  

而不是您可能也使用了。

I'm in the process of learning functional programming, and completely getting rid of for loops has been a challenge sometimes, because they provide so much control and freedom. Below is an example of checking if a string is an isogram or not (no letters should be repeated). With nested for loops, it became an easy solution. Is there a way to do this the functional way with any high order functions or anything else? Any suggestion would be a huge help.

Code:

function isIsogram(string) {
  let array = string.split('');
  let condition = true;
  for (let i = 0; i < string.length; i++) { //first loop picks character
    for (j = i + 1; j < string.length; j++) { //second loop compares it rest
      if (array[i].toLowerCase() == array[j].toLowerCase())
        condition = false; //if repeat, the condition false
    }
    return condition;
  }
}

解决方案

You can use every or some together with a suitable string function:

function isIsogram(string) {
    string = string.toLowerCase(); // case insensitive
    return string.split('').every(function(character, index) {
        return !string.includes(character, index+1);
    });
}

Instead of includes you might also have utilised indexOf.

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