generateReport_ DOM_ JS Advanced

function generateReport() {
    let bodyRowsRef = document.querySelectorAll("tbody tr");
    let headRowsRef = document.querySelectorAll("thead tr th input");
    let columnPosition = [];
    for (let index = 0; index < headRowsRef.length; index++) {

        if ( headRowsRef[index].checked == true){
            columnPosition.push(index);
        }
    }
    let finalResult = [];
    // let data = document.querySelectorAll("tbody tr");

    for (let j = 0; j < bodyRowsRef.length; j ++) {
        let currRow = bodyRowsRef[j].children;
        let currItems = {};
        for (let k = 0; k < currRow.length; k ++) {
            if (columnPosition.includes(k)) {
                let label = headRowsRef[k].name;
                currItems[label] = currRow[k].textContent;
            }
        }
        finalResult.push(currItems);
    }

    let jsonFinal = JSON.stringify(finalResult);
    let target = document.getElementById('output');
    target.value = jsonFinal;
}