Prefer querySelector
over getElementById
, querySelectorAll
over getElementsByClassName
and getElementsByTagName
They are not faster than querySelector
and it's better to be consistent.
document.getElementById('foo');
document.getElementsByClassName('foo bar');
document.getElementsByTagName('main');
document.getElementsByClassName(fn());
document.querySelector('#foo');
document.querySelector('.bar');
document.querySelector('main #foo .bar');
document.querySelectorAll('.foo .bar');
document.querySelectorAll('li a');
document.querySelector('li').querySelectorAll('a');