Interlace Arbitrary Strings created by oliverjam - https://repl.it/E7Hk/1

Interlace Arbitrary Strings.js

function combineStrings() {
  let result = '';
  if (arguments.length > 0) {
    const args = [...arguments];
    const maxLength = args.map(item => item.length).reduce((a, b) => Math.max(a, b));
    for (let i = 0; i < maxLength; i++) {
      args.forEach(item => {
        result += item.charAt(i);
      });
    }
  }
  return result;
}

combineStrings('abc', '123');