Doing without jQuery

Edit: You Might Not Need jQuery is a great resource that's probably better than mine.

I don't have to tell you that jQuery is fantastic and saves tons of time.

In some cases, you only need a small subset of its features and don't need to load the whole thing. Below is a quick reference for how to do things without jQuery -- sometimes in vanilla JavaScript, sometimes with smaller libraries. This reference is not comprehensive; I omit things because (1) I feel they should be left to jQuery (2) I am lazy.

In general

• Zepto is a much smaller version of jQuery that is almost indistinguishable, but it drops support for older browsers and IE.
• jQuery is made with compatibility in mind. Some of these options might not be -- use at your own risk.
• It might not make sense to load smaller libraries if jQuery is already cached via a CDN like Google's. Upsides of smaller libraries: shorter load if not cached, faster execution time. Downsides: slower load if jQuery is cached, less thinking for you as the developer. Your call.
• This guide is also available as plain text (because that's how I keep it!).

Selectors

Selecting by ID:

$('#foo')
document.getElementById('foo')

Selecting by class (not compatible with IE6-8, but good with everything else):

$('.bar')
document.getElementsByClassName('bar')

Selecting by tag name:

$('span')
document.getElementsByTagName('span')

Selecting sub-elements:

$('#foo span')
document.getElementById('foo').getElementsByTagName('span')

Selecting "special" elements:

$('html')
document.documentElement

$('head')
document.head

$('body')
document.body

There are a number of libraries that have jQuery's selector functionality; my favorite is the tiny Qwery.

Attributes

Getting/setting HTML:

$('#foo').html()
document.getElementById('foo').innerHTML

$('#foo').html('Hello, world!')
document.getElementById('foo').innerHTML = 'Hello, world!'

Dealing with classes:

$('#foo').addClass('bar')
document.getElementById('foo').className += ' bar '

$('#foo').removeClass('bar')
document.getElementById('foo').className = document.getElementById('foo').className.replace(/\bbar\b/gi, '')

$('#foo').hasClass('bar')
document.getElementById('foo').className.search(/\bbar\b/gi) !== -1

Getting an input's value:

$('#foo').val()
document.getElementById('foo').value

Effects

Showing and hiding:

$('#foo').show()
document.getElementById('foo').style.display = ''

$('#foo').hide()
document.getElementById('foo').style.display = 'none'

Changing CSS:

$('#foo').css('background-color', 'red')
document.getElementById('foo').style.backgroundColor = 'red'

For animation, use the Morpheus library.

Events

Document ready

If you're like me, the most common event you use is jQuery's $(document).ready (or some version of it). Two ways to do this.

First, do it the way MDN does it:

document.onreadystatechange = function() {
    if (document.readyState === 'complete') {
        // DOM is ready!
    }
};

Second, use domReady, a tiny library that's used like this:

domready(function() {
    // DOM is ready!
});

Clicks

$('#foo').click(function() { ... })
document.getElementById('foo').onclick = function() { ... }

All other events

If you don't want to use jQuery, use Bean. It's good stuff.

AJAX

If you don't want to use jQuery, use the Reqwest library.

Utilities

Parsing JSON:

jQuery.parseJSON(json)
JSON.parse(json)
// The JSON object isn't in older browsers, so you can include it if it's not there.
// http://github.com/douglascrockford/JSON-js/blob/master/json2.js

Conclusion

If this shows you anything, it's that jQuery saves you from a fair bit of headache. If you've thought about it and you still want to avoid jQuery, I hope this reference can help you!