Glow JS 0-01 Associative Array (javascript)

/** Glow JS 0-01 Associative Array by Timothy Robert Keal **/

function array_dump_this(element, index, array) {
  document.body.innerHTML+=('<font color="green">a[<font color="red">' + index + '</font>]="<font color="red">' + element + '</font>"</font><br>');
}

function array_dump(array) {
  array.forEach(array_dump_this)
}

function addToArray(array) {
  array.push(prompt("Add items to array or 'q' to stop"));
  if (array[array.length - 1] == 'q') {
    array.pop();
    array_dump(array);
  } else {
    addToArray(array);
  }
}

function addslashes(string) {
  return string.replace(/\\/g, '\\\\').
  replace(/\u0008/g, '\\b').
  replace(/\t/g, '\\t').
  replace(/\n/g, '\\n').
  replace(/\f/g, '\\f').
  replace(/\r/g, '\\r').
  replace(/'/g, '\\\'').
  replace(/"/g, '\\"');
}

function unicode_toHex(label = '') {
  var ret = '';
  var unicode = '';
  for (var offset = 0; offset < label.length; offset++) {
    unicode = parseInt(label.charCodeAt(offset), 10).toString(16);
    ret += parseInt(unicode.length, 10).toString(16) + unicode;
  }
  return ret;
}

function array_op(mode = 'set', array = 'aa', arg_label = '', arg_value = 1) {
  var label = unicode_toHex(arg_label);
  var addr = array;
  var addr_last = '';
  var i = 0;
  for (var offset = 0; offset < label.length; offset++) {
    addr_last = addr;
    addr += '[' + parseInt(label.substring(offset, offset), 16) + ']';
    if (eval(addr + '===undefined')) for (i = 0; i <= 16; i++)
        eval(addr_last + '.push(\'\');');
    }
    if (eval(addr + '[16]===undefined')) for (i = 0; i <= 16; i++)
        eval(addr + '.push(\'\');'); addr += '[16]';
      switch (mode) {
        case 'get':
          return eval(addr);
          break;
        case 'set':
          return eval(addr + '=\'' + addslashes(arg_value) + '\'');
          break;
        case 'inc':
          return eval(addr + '+=' + arg_value);
          break;
        case 'dec':
          return eval(addr + '-=' + arg_value);
        case 'append':
          return eval(addr + '+=\'' + addslashes(arg_value) + '\'');
          break;
        case 'seek':
          return addr;
          break;
        default:
        return;
      }
    }