有什么方法可以用来递增字母？

Question

有什么方法可以用来递增字母？

132

有没有人知道一个JavaScript库（如underscore、jQuery、MooTools等）可以提供递增字母的方法？

我想要做类似这样的事情：

"a"++; // would return "b"

- andyzinsser

我不确定你要寻找的“语法”是可能的，但可以通过方法实现操作。 - anson

什么是应用程序？ - valentinas

16个回答

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可以查看英文原文，
原文链接

- AutoBaker · Answer 1

Zar和Nathan的回答都很好。对我来说，这里的其他所有内容似乎都过于复杂了。

我想指定自己的字符集，因此没有使用charCode。
我不需要多字符递归。
向我的字符集中添加了0以进行错误处理（while (letter != 0)）。

最终我得到了这个：

let letter = "a";
let alphabet = "abcdefghijklmnopqrstuvwxyz0";
let nextletter = alphabet.substr(alphabet.indexOf(letter)+1,1);

然后我可以非常简单地添加更多维度：

let alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!£$%^&*_0";

function increment(e) {
let letter = e.value;
let alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0";
let next = alphabet.substr(alphabet.indexOf(letter)+1,1);
document.getElementById("result").innerHTML = next;
};

<input type="text" minlength="1" maxlength="1" onchange="increment(this)" placeholder="type letter">
<button>Update</button>
<div id="result"></div>

- Stephen Quan · Answer 2

这是我在https://dev59.com/C3RB5IYBdhLWcg3wc3A0#28490254上提交的rot13算法的变体：

function rot1(s) {
  return s.replace(/[A-Z]/gi, c =>
    "BCDEFGHIJKLMNOPQRSTUVWXYZAbcdefghijklmnopqrstuvwxyza"[
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".indexOf(c) ] )
}

底部的输入代码和顶部的查找编解码是相同的（即输出代码与输入代码相同，但向右移动1个位置）。该函数仅更改字母，即如果传入任何其他字符，则此编解码将不会更改它。

- dean schmid · Answer 3

一个只是为了好玩的解决方案。

function nextLetter(str) {
  const Alphabet = [
    // lower case alphabet
    "a", "b", "c",
    "d", "e", "f",
    "g", "h", "i",
    "j", "k", "l",
    "m", "n", "o",
    "p", "q", "r",
    "s", "t", "u",
    "v", "w", "x",
    "y", "z",
    // upper case alphabet
    "A", "B", "C",
    "D", "E", "F",
    "G", "H", "I",
    "J", "K", "L",
    "M", "N", "O",
    "P", "Q", "R",
    "S", "T", "U",
    "V", "W", "X",
    "Y", "Z"
  ];

  const LetterArray = str.split("").map(letter => {
    if (Alphabet.includes(letter) === true) {
      return Alphabet[Alphabet.indexOf(letter) + 1];
    } else {
      return " ";
    }
  });

  const Assemble = () => LetterArray.join("").trim();
  return Assemble();
}


console.log(nextLetter("hello*3"));

- Quentin 2 · Answer 4

在闭包中创建一个带有 {a: 'b', b: 'c', etc} 的函数：

let nextChar = (s => (
    "abcdefghijklmopqrstuvwxyza".split('')
    .reduce((a,b)=> (s[a]=b, b)), // make the lookup
c=> s[c] // the function returned
))({}); // parameter s, starts empty

用法：

nextChar('a')

添加大写字母和数字：

let nextCh = (
    (alphabeta, s) => (
        [alphabeta, alphabeta.toUpperCase(), "01234567890"]
            .forEach(chars => chars.split('')
               .reduce((a,b) => (s[a]=b, b))), 
        c=> s[c] 
    )
)("abcdefghijklmopqrstuvwxyza", {});

p.s. 在某些版本的 Javascript 中，您可以使用 [...chars] 替代 chars.split('')

- Gowtham Sooryaraj · Answer 5

基于 @Nathan wall 的答案，进行增量和减量操作

// Albhabet auto increment and decrement
class StringIdGenerator {
    constructor(chars = '') {
      this._chars = chars;
    }

  next() {
    var u = this._chars.toUpperCase();
    if (this._same(u,'Z')){
        var txt = '';
        var i = u.length;
        while (i--) {
            txt += 'A';
        }
        this._chars = txt+'A';
        return (txt+'A');
    } else {
      var p = "";
      var q = "";
      if(u.length > 1){
          p = u.substring(0, u.length - 1);
          q = String.fromCharCode(p.slice(-1).charCodeAt(0));
      }
      var l = u.slice(-1).charCodeAt(0);
      var z = this._nextLetter(l);
      if(z==='A'){
        this._chars = p.slice(0,-1) + this._nextLetter(q.slice(-1).charCodeAt(0)) + z;
          return p.slice(0,-1) + this._nextLetter(q.slice(-1).charCodeAt(0)) + z;
      } else {
        this._chars = p+z;
          return p + z;
      }
    }
  }

  prev() {
    var u = this._chars.toUpperCase();
    console.log("u "+u)
    var l = u.slice(-1).charCodeAt(0);
    var z = this._nextLetter(l);
    var rl = u.slice(1)
    var y = (rl == "A") ? "Z" :this._prevLetter(rl.charCodeAt(0))
      var txt = '';
      var i = u.length;
      var j = this._chars
      var change = false
      while (i--) {
        if(change){
          if (u[u.length-1] == "A"){
            txt += this._prevLetter(u[i].charCodeAt(0))
          }else{
            txt += u[i]
          }
          
        }else{
          if (u[u.length-1] == "A"){
            txt += this._prevLetter(u[i].charCodeAt(0))
            change = true
          }else{
            change = true
            txt += this._prevLetter(u[i].charCodeAt(0))
          }
        }
      }
      if(u == "A" && txt == "Z"){
        this._chars = ''
      }else{
        this._chars = this._reverseString(txt);
      }
      console.log(this._chars)
      return (j);
  }
  _reverseString(str) {
      return str.split("").reverse().join("");
  }
  _nextLetter(l){
      if(l<90){
          return String.fromCharCode(l + 1);
      }
      else{
          return 'A';
      }
  }

  _prevLetter(l){
    if(l<=90){
      if(l == 65) l = 91
        return String.fromCharCode(l-1);
    }
    else{
        return 'A';
    }
  }
  _same(str,char){
      var i = str.length;
      while (i--) {
          if (str[i]!==char){
              return false;
          }
      }
      return true;
  }
    
}

用法

const ids = new StringIdGenerator();

ids.next(); 
ids.prev();

- LokeshKumar · Answer 6


function charLoop(from, to, callback) {
    var i = from.charCodeAt(0);
    var to = to.charCodeAt(0);
    for (; i <= to; i++) {
        callback(String.fromCharCode(i));
    }
}

var sequence = "";
charLoop("A", "Z", function (char) {
    sequence += char + " ";
});

sequence = sequence.trim();
sequence = sequence.split(" ");

var resseq = sequence;
var res = "";
var prevlet = "";
var nextlet = "";

for (b = 0; b < resseq.length; b++) {
    if (prevlet != "") {
        prevlet = resseq[b];
    }

    for (a = 0; a < sequence.length; a++) {
        for (j = 1; j < 100; j++) {
            if (prevlet == "") {
                prevlet = sequence[a];
                nextlet = sequence[a + 1];
                res += sequence[a] + sequence[a] + 0 + j + " ";
            }
            else {

                if (j < 10) {
                    res += prevlet + sequence[a] + 0 + j + " ";
                }
                else {
                    res += prevlet + sequence[a] + j + " ";
                }
            }
        }
    }
}

document.body.innerHTML = res;