创建指定范围内的字符数组 [英] Create an array of characters from specified range

问题描述

我读了一些用Ruby编写的代码:

I read some code where someone did this in Ruby:

puts ('A'..'Z').to_a.join(',')

输出:

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

Javascript 中是否有某些东西可以使之轻松实现?如果没有，是否有Node模块可以允许类似的东西?

Is there something in Javascript that will allow this to be done just as easy? if not, is there Node module that allows for something similar?

推荐答案

JavaScript本身没有该功能.在下面，您可以找到一些有关如何解决该问题的示例:

Javascript doesn't have that functionality natively. Below you find some examples of how it could be solved:

正常功能，基本平面中的任何字符(不检查代理对)

Normal function, any characters from the base plane (no checking for surrogate pairs)

function range(start,stop) {
  var result=[];
  for (var idx=start.charCodeAt(0),end=stop.charCodeAt(0); idx <=end; ++idx){
    result.push(String.fromCharCode(idx));
  }
  return result;
};

range('A','Z').join();

与上面相同，但作为添加到数组原型的函数，因此可用于所有数组:

The same as above, but as a function added to the array prototype, and therefore available to all arrays:

Array.prototype.add_range = function(start,stop) {
  for (var idx=start.charCodeAt(0),end=stop.charCodeAt(0); idx <=end; ++idx){
    this.push(String.fromCharCode(idx));
  }
  return this;
};

[].add_range('A','Z').join();

预选字符的范围.比上面的函数快，并且让您使用 alphanum_range('A'，'z')表示A-Z和a-z:

A range from preselected characters. Is faster than the functions above, and let you use alphanum_range('A','z') to mean A-Z and a-z:

var alphanum_range = (function() {
  var data = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'.split('');
  return function (start,stop) {
    start = data.indexOf(start);
    stop = data.indexOf(stop);
    return (!~start || !~stop) ? null : data.slice(start,stop+1);
  };
})();

alphanum_range('A','Z').join();

或ascii范围内的任何字符.通过使用缓存的数组，它比每次构建数组的函数都要快.

Or any character from the ascii range. By using a cached array, it is faster than the functions that build the array every time.

var ascii_range = (function() {
  var data = [];
  while (data.length < 128) data.push(String.fromCharCode(data.length));
  return function (start,stop) {
    start = start.charCodeAt(0);
    stop = stop.charCodeAt(0);
    return (start < 0 || start > 127 || stop < 0 || stop > 127) ? null : data.slice(start,stop+1);
  };
})();

ascii_range('A','Z').join();

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