Best Practices for Front-End Django Developers

BEST PRACTICES FOR
FRONT-END DJANGO
DEVELOPERS
Presentation by Christine Cheung

About the Presenter

Front End Developer at RED Interactive Agency

PyLadies board member

http://www.xtine.net

@webdevgirl

Best Practices for Front-End Django Developers by Christine Cheung - DjangoCon 2011

Presentation is Important

Polished front-end is as important as the back-end

It may “scale” ...

But bloated markup and JavaScript will slow performance

The implementation of the design is what the user notices.


Start Organized
Structure the hierarchy of static and template files.

Folders for each app in templates


Starting Templates

Start with base.html

Extend from there - index/about/contact.html etc

Blocks for common elements {% block title %} {% endblock title %}

Include template files {% include "foo.html" %}


Template Tags and Filters
The template system is meant to express presentation, not logic

Presentation and iteration over data, NOT manipulation

Make your own template tag
from django import template
Example
register = template.Library()

def dashreplace(value, arg):
return value.replace(arg, '-')

register.filter('dashreplace', dashreplace)


Cascading Style Sheets
+ Header / #header
Define a Style Guide
+ Content / #content
- Left column / #leftcolumn
Consistent Variable Naming - Right column / #rightcolumn
- Sidebar / #sidebar
- Search / #search
Camel Case vs Dashes + Footer / #footer

Advertisements .ads
Organize into separate files Content header h2

Dark grey (text): #333333
Dark Blue (headings, links) #000066


Using a JavaScript Library

Use only one library (jQuery) and stick to it!

Avoid plug-in overkill, no more than 3-4

Reduce performance hits and code conflicts.

Analyze if you can write your own.


JavaScript Namespacing

var someNamespace = (function() {
Namespace your JavaScript
var animal = “pony”;

Prevent conflicts var greeting = function () {
return “I’m a ” + animal;
};

Easier to read and maintain return {

foo : function() {
Don’t have to use $(document).ready()
},
// do stuff here

bar : function() {
// do stuff here
}

};

})();


JavaScript Don’ts
DO NOT:
document.write('foo');

<a
onclick="myClickFunction()"
href="http://foo.com"></a>

<a
href="javascript:doSomething()"></a>

DO:
<a
class="link"
href="http://foo.com"></a>

$('.link').click(function() { // do stuff });


Heavy Usage of JavaScript

For front-end heavy websites, check out Backbone.js

Hook up with RESTful interfaces (TastyPie)

Underscore.js for more utility functions

object and data manipulation


Don’t Start HTML from
Scratch

HTML5 Boilerplate
base.html starting point

CSS Reset (normalize.css)

jQuery + Modernizr


Modernizr

JavaScript library to detect HTML5 + CSS3 technologies

Detect the features, NOT the browser

HTML5 elements for IE


Modernizr Examples

.no-cssgradients { Modernizr.load({
background: url("images/glossybutton.png");
test: Modernizr.geolocation,
}
yep : 'geo.js',
.cssgradients { nope: 'geo-polyfill.js'
background-image: linear-gradient(top, #555, #333); });
}


Compass Framework
CSS Authoring Framework + Utilities
SASS - nested rules, variables, mixins
Image Spriting
$blue = #010db5;

@include border-radius(4px, 4px); #navbar {
width: 80%;
-webkit-border-radius: 4px 4px;
height: 23px;
-moz-border-radius: 4px / 4px;
ul { list-style-type: none; }
-o-border-radius: 4px / 4px;
li {
-ms-border-radius: 4px / 4px;
float: left;
-khtml-border-radius: 4px / 4px;
a { font-weight: bold; }
border-radius: 4px / 4px; } &:last-child { color: $blue; }
}
}


Compass Integration

django-compass

PyScss

SASS Compiler for Python

Tip: Don’t deploy Compass, put it in project root folder


All About the Data

Leverage the power of both the front and back end

Share the work between them

Class Based Views for quick prototyping

Beware of Caching


Define Your Data Types

Before any coding happens:

Write out the API - evaluate the design

Know when to make a View vs API

Context Processors


Let’s Test!
CSSLint
JSLint
warning: will make you cry

Google Closure Compiler

function hello(name) {
alert('Hello, ' + name); function hello(a){alert("Hello,
} "+a)}hello("New user");

hello('New user');


Performance Tips

Build script(s) to minify and gzip files
TEMPLATE_DEBUG

settings flag to toggle between flat/compiled static files

Asynchronous / lazy loading JavaScript


Wrap Up
Consistent folder structures and document style guides

Use a JavaScript library and modern authoring techniques

Leverage data loading between the front and the back ends

Use HTML Boilerplate + CSS/JS tools to your advantage

Think about testing and performance of front-end code


Resources
CSS Style Guide: http://coding.smashingmagazine.com/2008/05/02/improving-code-
readability-with-css-styleguides/

Front-End Development Guidelines: http://taitems.github.com/Front-End-Development-
Guidelines/

Outdated JavaScript: http://davidbcalhoun.com/2011/how-to-spot-outdated-javascript

Namespaces in JavaScript: http://blog.stannard.net.au/2011/01/14/creating-namespaces-in-
javascript/

HTML5 Boilerplate: http://html5boilerplate.com/

Compass Framework: http://compass-lang.com/

SASS: http://sass-lang.com/


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