How could this one be tweaked so that it could increment a set of two letters, so that it'd look like this:

AA, AB, AC...AZ, BA, BB, BC, etc

This is borrowed from tckmn, but it addresses one letter only.

var alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('')
function incrementChar(c) {
    var index = alphabet.indexOf(c)
    if (index == -1) return -1 // or whatever error value you want
    return alphabet[index   1 % alphabet.length]
}

Appreciate your help!

CodePudding user response：

You just need two loops. One to iterate over the alphabet, and the second to iterate over the alphabet on each iteration of the first loop.

const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

const arr = [];

for (let i = 0; i < alphabet.length; i  ) {
  for (let j = 0; j < alphabet.length; j  ) {
    arr.push(`${alphabet[i]}${alphabet[j]}`);
  }  
}

console.log(arr);

CodePudding user response：

In your situation, how about the following modification? In this modification, I added a wrapper function for using 2 letters.

Modified script:

// This is from your showing script.
var alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('')
function incrementChar(c) {
  var index = alphabet.indexOf(c)
  if (index == -1) return -1 // or whatever error value you want
  return alphabet[index   1 % alphabet.length]
}

// I added this function.
function wrapper(str) {
  const [a, b] = [...str];
  const r1 = incrementChar(a);
  const r2 = incrementChar(b);
  return (r2 ? [a, r2] : (r1 ? [r1, "A"] : ["over"])).join("");
}

function main() {
  var samples = ["AA", "AY", "AZ", "ZY", "ZZ"]; // This is a sample value for testing this script.
  const res = samples.map(e => wrapper(e));
  console.log(res); // [ 'AB', 'AZ', 'BA', 'ZZ', 'over' ]
}

main();

• When this script is run, [ 'AB', 'AZ', 'BA', 'ZZ', 'over' ] is returned. From your showing script, when Z is put, undefined is returned. So, in this sample, over is returned.