Prevent the default action of an event

ele.onclick = function(e) {
    // Do some thing
    ...

    return false;
};

<form>
    <button type="submit" onclick="return false">Click</button>
</form>

<button type="submit" onclick="event.preventDefault()">Click</button>

ele.onclick = function(e) {
    e.preventDefault();

    // Do some thing
    ...
};

ele.addEventListener('click', function(e) {
    e.preventDefault();
    ...
});