let myList = [
    {id: 'li1', condition: ''},
    [
        {id: 'li2', condition: 'AND'},
        {id: 'li3', condition: 'OR'},
    ],
    [
        {id: 'li4', condition: 'OR'},
        {id: 'li5', condition: 'AND'},
    ]
]

generateString = (list) => {
  let newString, start;

  for (let i = 0; i < list.length; i++) {
    let listItem = list[i];
    if (isArray(listItem)) {
      newString = generateString(listItem);
    } else {
      if (filter.id === 'C1') {
        newString = `(${filter.id})`;
      } else {
        newString = `(${filter.condition} ${filter.id})`;
      }
    }
  }