Earlier quoted context omitted.
jQuery API is not pretty
I'll take $('p').text('Hello.') over for (var p in document.getElementsByTagName('p')) { p.innerHTML = 'Hello.'; } any day!
ps. second example is not valid, in Vanilla JS you do it like this:
document.getElementsByTagName('p').filter(function(el) {
el.innerHTML = 'Hello.';
});