Create an array of characters from specified range

Question

I read some code where someone did this in Ruby:

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

output:

A,B,C,D,E,F,G,H,I,J,K,L,M,N,O         


        

Answer 1

No, JavaScript does not have any built-in Range object. You would need to write a function to create an abstract Range, and then add a to_a method for the equivalence.

For fun, here's an alternative way to get that exact output, with no intermediary strings.

function commaRange(startChar,endChar){
  var c=','.charCodeAt(0);
  for (var a=[],i=startChar.charCodeAt(0),e=endChar.charCodeAt(0);i<=e;++i){
    a.push(i); a.push(c);
  }
  a.pop();
  return String.fromCharCode.apply(String,a);
}

console.log(commaRange('A','J')); // "A,B,C,D,E,F,G,H,I,J"

For Node.js, there is the Lazy module.