While most of Django core is Python, the admin and gis contrib apps
contain JavaScript code.
Please follow these coding standards when writing JavaScript code for inclusion in Django.
Please conform to the indentation style dictated in the .editorconfig
file. We recommend using a text editor with EditorConfig support to avoid
indentation and whitespace issues. Most of the JavaScript files use 4 spaces
for indentation, but there are some exceptions.
When naming variables, use camelCase instead of underscore_case.
Different JavaScript files sometimes use a different code style. Please try to
conform to the code style of each file.
Use the JSHint code linter to check your code for bugs and style errors. JSHint will be run when you run the JavaScript tests. We also recommended installing a JSHint plugin in your text editor.
Where possible, write code that will work even if the page structure is later
changed with JavaScript. For instance, when binding a click handler, use
$('body').on('click', selector, func) instead of
$(selector).click(func). This makes it easier for projects to extend
Django’s default behavior with JavaScript.
Django’s admin system leverages the jQuery framework to increase the capabilities of the admin interface. In conjunction, there is an emphasis on admin JavaScript performance and minimizing overall admin media file size. Serving compressed or “minified” versions of JavaScript files is considered best practice in this regard.
To that end, patches for JavaScript files should include both the original
code for future development (e.g. foo.js), and a compressed version for
production use (e.g. foo.min.js). Any links to the file in the codebase
should point to the compressed version.
To simplify the process of providing optimized JavaScript code, Django includes a handy Python script which should be used to create a “minified” version. To run it:
$ pip install closure
$ python django/contrib/admin/bin/compress.py
Behind the scenes, compress.py is a front-end for Google’s
Closure Compiler which is written in Java. The Closure Compiler library is
not bundled with Django, but you can install it using pip as done above. The
Closure Compiler library requires Java 7 or higher.
Please don’t forget to run compress.py and include the diff of the
minified scripts when submitting patches for Django’s JavaScript.
Django’s JavaScript tests can be run in a browser or from the command line.
The tests are located in a top level js_tests directory.
Django’s JavaScript tests use QUnit. Here is an example test module:
QUnit.module('magicTricks', {
beforeEach: function() {
var $ = django.jQuery;
$('#qunit-fixture').append('<button class="button"></button>');
}
});
QUnit.test('removeOnClick removes button on click', function(assert) {
var $ = django.jQuery;
removeOnClick('.button');
assert.equal($('.button').length, 1);
$('.button').click();
assert.equal($('.button').length, 0);
});
QUnit.test('copyOnClick adds button on click', function(assert) {
var $ = django.jQuery;
copyOnClick('.button');
assert.equal($('.button').length, 1);
$('.button').click();
assert.equal($('.button').length, 2);
});
Please consult the QUnit documentation for information on the types of assertions supported by QUnit.
The JavaScript tests may be run from a web browser or from the command line.
To run the tests from a web browser, open up js_tests/tests.html in your
browser.
To measure code coverage when running the tests, you need to view that file over HTTP. To view code coverage:
Execute python -m http.server from the root directory (not from inside
js_tests).
Open http://localhost:8000/js_tests/tests.html in your web browser.
To run the tests from the command line, you need to have Node.js installed.
After installing Node.js, install the JavaScript test dependencies by running the following from the root of your Django checkout:
$ npm install
Then run the tests with:
$ npm test
Dec 25, 2023