#18826: A bit changed JavaScript for CSRF with async JS
-------------------------------------+-------------------------------------
Reporter: panco | Owner: nobody
Type: | Status: closed
Cleanup/optimization | Version: 1.4
Component: Documentation | Resolution:
Severity: Normal | worksforme
Keywords: ajax, csrf | Triage Stage: Design
Has patch: 0 | decision needed
Needs tests: 0 | Needs documentation: 0
Easy pickings: 0 | Patch needs improvement: 0
| UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by lrekucki):
* cc: lrekucki@… (added)
Old description:
> Recently I've found use for the code found at
> https://docs.djangoproject.com/en/dev/ref/contrib/csrf/#ajax
> and as I can't sleep well if my JS doesn't pass some of the basic JSlint
> standards I've changed the snippet a bit:
> {{{
> jQuery(document).ajaxSend(function (event, xhr, settings) {
> function getCookie(name) {
> var cookieValue = null, cookies = [], i = 0, j = 0,
> cookie = {};
> if (document.cookie && document.cookie !== '') {
> cookies = document.cookie.split(';');
> for (j = cookies.length; i < j; i += 1) {
> cookie = jQuery.trim(cookies[i]);
> // Does this cookie string begin with the
> name we want?
> if (cookie.substring(0, name.length + 1)
> === (name + '=')) {
> cookieValue =
> decodeURIComponent(cookie.substring(name.length + 1));
> break;
> }
> }
> }
> return cookieValue;
> }
>
> function sameOrigin(url) {
> // url could be relative or scheme relative or absolute
> var host = document.location.host, // host + port
> protocol = document.location.protocol,
> sr_origin = '//' + host,
> origin = protocol + sr_origin;
> // Allow absolute or scheme relative URLs to same origin
> return (url === origin || url.slice(0, origin.length + 1)
> === origin + '/') || (url === sr_origin || url.slice(0, sr_origin.length
> + 1) === sr_origin + '/') || // or any other URL that isn't scheme
> relative or absolute i.e relative.
> !(/^(\/\/|http:|https:).*/.test(url));
> }
>
> function safeMethod(method) {
> return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
> }
>
> if (!safeMethod(settings.type) && sameOrigin(settings.url)) {
> xhr.setRequestHeader("X-CSRFToken",
> getCookie('csrftoken'));
> }
> });
> }}}
>
> * "===" instead of "=="
> * all vars at the beginning of the function (and all the changes that
> brings forth)
>
> I realize these changes are very small, but I think since this is a
> simple copy/paste snippet it should be of the highest quality possible
> (there's room for improvement still).
> I'm using it and it performs as intended.
New description:
Recently I've found use for the code found at
https://docs.djangoproject.com/en/dev/ref/contrib/csrf/#ajax
and as I can't sleep well if my JS doesn't pass some of the basic JSlint
standards I've changed the snippet a bit:
{{{
#!javascript +line-numbers
jQuery(document).ajaxSend(function (event, xhr, settings) {
function getCookie(name) {
var cookieValue = null, cookies = [], i = 0, j = 0, cookie
= {};
if (document.cookie && document.cookie !== '') {
cookies = document.cookie.split(';');
for (j = cookies.length; i < j; i += 1) {
cookie = jQuery.trim(cookies[i]);
// Does this cookie string begin with the
name we want?
if (cookie.substring(0, name.length + 1)
=== (name + '=')) {
cookieValue =
decodeURIComponent(cookie.substring(name.length + 1));
break;
}
}
}
return cookieValue;
}
function sameOrigin(url) {
// url could be relative or scheme relative or absolute
var host = document.location.host, // host + port
protocol = document.location.protocol,
sr_origin = '//' + host,
origin = protocol + sr_origin;
// Allow absolute or scheme relative URLs to same origin
return (url === origin || url.slice(0, origin.length + 1)
=== origin + '/') || (url === sr_origin || url.slice(0, sr_origin.length +
1) === sr_origin + '/') || // or any other URL that isn't scheme relative
or absolute i.e relative.
!(/^(\/\/|http:|https:).*/.test(url));
}
function safeMethod(method) {
return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
}
if (!safeMethod(settings.type) && sameOrigin(settings.url)) {
xhr.setRequestHeader("X-CSRFToken",
getCookie('csrftoken'));
}
});
}}}
* "===" instead of "=="
* all vars at the beginning of the function (and all the changes that
brings forth)
I realize these changes are very small, but I think since this is a simple
copy/paste snippet it should be of the highest quality possible (there's
room for improvement still).
I'm using it and it performs as intended.
--
Comment:
I mainly meant things like:
* 8 spaces of indentation;
* very long line ending with a comment;
* initializing {{{cookie}}} to an object while it's later assigned a
string;
* not initializing value of {{{i}}} in the loop while initializing a
{{{j}}} with list length for a premature optimization.
Changing to {{{===}}} is ok, while hoisting all the variables to the top,
IMHO, actually makes the code less readable (but it's probably a matter of
taste).
--
Ticket URL: <https://code.djangoproject.com/ticket/18826#comment:5>
Django <https://code.djangoproject.com/>
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