Parse nested ul to nested array in js

Question

How to parse nested ul of any depth to nested array keeping ul structure. Example:

<ul>
    <li class="operator">operator1</li>
    <ul>
        <li class="operator">operator2</li>
        <ul>
            <li  class="condition">condition 1</li>
            <li  class="condition">condition 2</li>
        </ul>
        <li  class="condition">condition3</li>
    </ul>

must be parsed to:

 [operator1,[operator2,[condition1],[condition2]],[condition3]]

i tried:

const parseListItems = (e) => {
            const listItems = e.querySelectorAll('li')
            const resultArray = []
            listItems.forEach(item => {
                const nestedUl = item.querySelector('ul')
                if (nestedUl) {
                    console.log('ul')
                    const nestedResult = parseListItems(nestedUl)
                } else {
                    console.log('li')
                }
            })

        }

but how to fill the array? The structure is allways [operator[condition/operator,condition/operator]] where condition/operator means condition is just text but operator can be again [operator[condition/operator,condition/operator]] in any depth. Ul have structure accordingly.

Answer 1

    <ul>
        <li class="operator">operator1
            <ul>
                <li class="operator">operator2
                    <ul>
                        <li class="condition">condition1</li>
                        <li class="condition">condition2</li>
                    </ul>
                </li>
                <li class="condition">condition3</li>
            </ul>
        </li>
    </ul>

document.addEventListener('DOMContentLoaded', () => {
    const parseListItems = (element) => {
        const listItems = element.children;
        const resultArray = [];

        Array.from(listItems).forEach(item => {
            if (item.tagName === 'LI') {
                const nestedUl = item.querySelector('ul');
                if (nestedUl) {
                    const nestedResult = parseListItems(nestedUl);
                    resultArray.push([item.firstChild.textContent.trim(), ...nestedResult]);
                } else {
                    resultArray.push(item.textContent.trim());
                }
            }
        });

        return resultArray;
    };

    const ulElement = document.querySelector('ul');
    const parsedList = parseListItems(ulElement);
    console.log(parsedList);
});