const toggleBlockUser = (ev) => {
    let row = getSpecificParentByName(ev.target, 'tr');
    let color = row.style.color;
    console.log(color);
    if(!color){
        color = 'lightgrey';
    }
    else{
        color = (color === 'black') ? 'lightgrey' : 'black';
    }
};

const getSpecificParentByName = (element, parentTagName) => {
    console.log(element.tagName);
    if(element.tagName.toLowerCase() !== parentTagName){
        element = getSpecificParentByName(element.parentElement, parentTagName);
    }
    return element;
};

let buttons = document.getElementsByName('block');
console.log(buttons);
for(let i = 0; i < buttons.length; i++){
    console.log(buttons[i]);
    buttons[i].addEventListener('click', toggleBlockUser, false);
}