$(…).each is not a function

1) Paste:

var script = document.createElement('script');
script.src = "https://ajax.googleapis.com/ajax/libs/jquery/1.6.3/jquery.min.js";
document.getElementsByTagName('head')[0].appendChild(script);

on your console (includes jQuery)

2) Wait 1 sec and paste:

var h2Arr = [];
$('h2').each( function() {
    h2Arr.push($(this).html());
});

Now, all contents of h2 tags of that page should be stored into h2Arr