What is Facebook's function __d - javascript

I'm working on a project that (hopefully) involves taking advantage of some of the javascript that's already built into Facebook. But right away I've got a roadblock in that I can't figure out what __d is.
If you look at the source javascript files, pretty much every command begins with __d
For example:
__d("legacy:live-timer",["LiveTimer"],function(a,b,c,d){a.LiveTimer=b('LiveTimer');},3);
But I can't find anywhere in any of the javascript files what __d actually does. Shouldn't it have to be defined somewhere for all these other functions to take advantage of it?
UPDATE:
So let's say there's a site with some javascript like this...
function alertSomething(var) {
if (var) alert("Here it is: "+var);
}
if (some condition) alertSomething("something");
Now let's say I had a Chrome Extension and I was able to inject my own Javascript into the page. Couldn't \my Chrome Extension Javascript have something like this...
if (some other condition) alertSomething("something else");
Thus I would be taking advantage of some code that exists in the javascript already on the page?

As, I have inspected Facebook JavaScript SDK. I believe that it uses Dependency Injection Mechanism. Here are two URLs.
Production: http://connect.facebook.net/en_US/all.js (obfuscated)
Development: http://connect.facebook.net/en_US/all/debug.js (deobfuscated)
If you check debug.js, you can see require, __d, __t and many more. __d is more like define function from RequireJS (http://requirejs.org/docs/api.html#define)
__d = function(/*string*/ id, /*array<string>*/ deps, factory,
/*number?*/ _special) {/*TC*/__t([id,'string','id'],[deps,'array<string>','deps'],[_special,'number?','_special']);/*/TC*/

I found the definition of __d on line 20 of 1LWPxIBQ4v0.js. No idea if the file is named the same for everyone. Search for "a.__d=function(s,t,u,v)" (a is the global object, i.e. window, effectively making __d a global function). Good luck with that de-minification though...

The function __d is API for RequireJS used to Define a Module.
Example:
__d('Example', [], function a(b, c, d, e, f, g, h) {
'use strict';
if (c.__markCompiled) c.__markCompiled();
f.exports = {
a: "Hello World"
};
}, null);
Call:
require('Example');
Output:
Object {a: "Hello World"}

Related

Javascript function is undefined only in IE11

I'm trying to use a template but just realized that the javascript doesn't work at all in IE.
It fails in several places but here is the first one:
I have this tag, immediately before my </html>:
<script>
document.addEventListener("DOMContentLoaded", function (event) {
navbarToggleSidebar();
navActivePage();
});
</script>
The exception says, "0x800a1391 - JavaScript runtime error: 'navbarToggleSidebar' is undefined occurred"
The javascript file that came with this template was minimized as uses some cracy javascript markup that I've never seen and do not understand. But when I do a find in the whole solution for navbarToggleSidebar I only find this:
JkW7: function (t, e, n) {
"use strict";
Object.defineProperty(e, "__esModule", {
value: !0
});
var i = (n("PExH"), n("juYr"), n("6wzU"), n("e9iq"), n("aWFY"));
! function (t) {
t.keys().map(t)
}(n("pax0")), Object.assign(window, {
masonryBuild: i.a,
navbarToggleSidebar: i.c,
navActivePage: i.b
})
},
I can post the whole file somewhere (just tell me where, it's too long to paste here) if that's helpful because this is clearly just a piece of a huge js thing that I don't understand at all. I like to think I'm fairly decent with js and jquery and this looks greek to me. And it all works beautifully in Chrome and FF.
Can anyone help me figure out what's going on?
Thanks!!
Well n is a callback function t is an array or a list of some kind most likely; so in order for you to figure out what is actually happening in the function you have to figure out where the function was actually invoked. It is much easier to find out what library was used and see if it is hosted anywhere in a non-minified version.
Sometimes this is done intentionally in order to protect developers from other people having an easy time engineering their solutions to programming problems.
Basically in order for anyone to figure out what the function actually does, you would have to print the entire page library, then trace through it, then when you are done after about a month you will have your answer.
Arrays, callback functions, as well as a probably system variable and object literals are used in that function.

IPython: Adding Javascript scripts to IPython notebook

As a part of a project, I need to embedd some javascripts inside an IPython module.
This is what I want to do:
from IPython.display import display,Javascript
Javascript('echo("sdfds");',lib='/home/student/Gl.js')
My Gl.js looks like this
function echo(a){
alert(a);
}
Is there some way so that I can embed "Gl.js" and other such external scripts inside the notebook, such that I dont have to include them as 'lib' argument everytime I try to execute some Javascript code which requires to that library.
As a very short-term solution, you can make use of the IPython display() and HTML() functions to inject some JavaScript into the page.
from IPython.display import display, HTML
js = "<script>alert('Hello World!');</script>"
display(HTML(js))
Although I do not recommend this over the official custom.js method, I do sometimes find it useful to quickly test something or to dynamically generate a small JavaScript snippet.
Embedding D3 in an IPython Notebook
https://blog.thedataincubator.com/2015/08/embedding-d3-in-an-ipython-notebook/
To summarize the code.
Import the script:
%%javascript
require.config({
paths: {
d3: '//cdnjs.cloudflare.com/ajax/libs/d3/3.4.8/d3.min'
}
});
Add an element like this:
%%javascript
element.append("<div id='chart1'></div>");
Or this:
from IPython.display import Javascript
#runs arbitrary javascript, client-side
Javascript("""
window.vizObj={};
""".format(df.to_json()))
IPython Notebook: Javascript/Python Bi-directional Communication
http://jakevdp.github.io/blog/2013/06/01/ipython-notebook-javascript-python-communication/
A more extensive post explaining how to access Python variables in JavaScript and vice versa.
I've been fighting with this problem for several days now, here's something that looks like it works; buyer beware though, this is a minimal working solution and it's neither pretty nor optimal - a nicer solution would be very welcome!
First, in .ipython/<profile>/static/custom/myScript.js, we do some require.js magic:
define(function(){
var foo = function(){
console.log('bar');
}
return {
foo : foo
}
});
Copy this pattern for as many functions as you like. Then, in .ipython/<profile>/static/custom/custom.js, drag those out into something persistent:
$([IPython.events]).on('notebook_loaded.Notebook', function(){
require(['custom/myScript'], function(custom){
window.foo = custom.foo;
} );
});
Yes, I am a horrible person for throwing stuff on the window object, namespace things as you deem appropriate. But now in the notebook, a cell like
%%javascript
foo();
should do exactly what it looks like it should, without the user having to explicitly import your JS. I would love to see a simpler solution for this (plz devs can we plz have $.getScript('/static/custom/util.js'); in custom.js to load up a bunch of global JS functions) - but this is the best I've got for now. This singing and dancing aside, HUGE ups to the IPython notebook team, this is an awesome platform!
Not out of the box by installing a package, at least for now.
The way to do it is to use custom.js and jQuery getScript to inject the js into the notebook.
I explicitly stay vague on how to do it, as it is a dev feature changing from time to time.
What you should know is that the static folder in user profile is merged with webserver static assets allowing you to access any file that are in this folder by asking for the right url.
Also this question has been asked a few hours ago on IPython weekly video "lab meeting" broadcasted live and disponible on youtube (you might have a longer answer), I've opened discussion with the author of the question here
For some reason, I have problems with IPython.display.Javascript. Here is my alternative, which can handle both importing external .js files and running custom code:
from IPython.display import display, HTML
def javascript(*st,file=None):
if len(st) == 1 and file is None:
s = st[0]
elif len(st) == 0 and file is not None:
s = open(file).read()
else:
raise ValueError('Pass either a string or file=.')
display(HTML("<script type='text/javascript'>" + s + "</script>"))
Usage is as follows:
javascript('alert("hi")')
javascript(file='Gl.js')
javascript('echo("sdfds")')
You can use IJavascript (a Javascript kernel for Jupyter notebooks).
I was interested in calling JavaScript from a Jupyter code (Python) cell to process strings, and have the processed string output in the (same) code cell output; thanks to Inject/execute JS code to IPython notebook and forbid its further execution on page reload and Why cannot python call Javascript() from within a python function? now I have this example:
from IPython.display import display, Javascript, Markdown as md, HTML
def js_convert_str_html(instring_str):
js_convert = """
<div id="_my_special_div"></div>
<script>
var myinputstring = '{0}';
function do_convert_str_html(instr) {{
return instr.toUpperCase();
}}
document.getElementById("_my_special_div").textContent = do_convert_str_html(myinputstring);
</script>
""".format(instring_str)
return HTML(js_convert)
jsobj = js_convert_str_html("hello world")
display(jsobj)
Note that the JavaScript-processed string does not get returned to Python per se; rather, the JavaScript itself creates its own div, and adds the result of the string conversion to it.

Starting with RequireJS, communication between modules

I am an ActionScript 3 developer who is just making his first way in building a large-scale JavaScript app.
So I understand modules and understand that AMD is a good pattern to use. I read about RequireJS and implemented it. However, what I still don't understand is how to achieve Cross-Module communication. I understand that there should be some kind of mediator...
I read articles and posts and still couldn't understand how to implement it simply.
Here is my code, simplified:
main.js
require(["Player", "AssetsManager"], function (player, manager) {
player.loadXML();
});
Player.js
define(function () {
function parseXml(xml)
{
// NOW HERE IS THE PROBLEM -- how do I call AssetsManager from here???
AssetsManager.queueDownload($(xml).find("prop").text());
}
return {
loadXML: function () {
//FUNCTION TO LOAD THE XML HERE, WHEN LOADED CALL parseXml(xml)
}
}
});
AssetsManager.js
define(function () {
var arrDownloadQueue = [];
return {
queueDownload: function(path) {
arrDownloadQueue.push(path);
}
}
});
Any "for dummies" help will be appreciated :)
Thank you.
To load up modules from another modules that you define(), you would simply set the first parameter as an array, with your module names in it. So let's say, in your code, you wanted to load Player.js into AssetsManager.js, you would simply include the string Player in the array.
This is simply possible because define's abstract implementation is equivalent to require, only that the callback passed to define expects a value to be returned, and that it will add a "module" to a list of dependencies that you can load up.
AssetsManager.js
define(['Player'], function (player) {
//... Your code.
});
However, if I can add to it, I personally prefer the use of require inside of the callback passed to define to grab the dependency that you want to load, instead of passing parameter to the callback.
So here's my suggestion:
define(['Player'], function () {
var player = require('Player');
});
And this is because it's much more in tune with CommonJS.
And this is how main.js would look like formatted to be more CommonJS-friendly:
require(["Player", "AssetsManager"], function () {
var player = require('Player');
var manager = require('AssetsManager');
player.loadXML();
});
But the CommonJS way of doing things is just a personal preference. My rationale for it is that the order in which you input the dependency names in the array might change at any time, and i wouldn't want to have to step through both the array and the parameters list.
Another rationale of mine (though, it's just pedantic), is that I come from the world of Node.js, where modules are loaded via require().
But it's up to you.
(This would be a reply to skizeey's answer, but I don't have enough reputation for that)
Another way of solving this problem without pulling in Player's AssetManager dependency via require is to pass the AssetManager instance that main.js already has around. One way of accomplishing this might be to make Player's loadXML function accept an AssetManager parameter that then gets passed to parseXml, which then uses it. Another way might be for Player to have a variable to hold an AssetManager which gets read by parseXml. It could be set directly or a function to store an AssetManager in the variable could be used, called say, setAssetManager. This latter way has an extra consideration though - you then need to handle the case of that variable not being set before calling loadXml. This concept is generally called "dependency injection".
To be clear I'm not advising this over using AMD to load it in. I just wanted to provide you with more options; perhaps this technique may come in handier for you when solving another problem, or may help somebody else. :)

jquery tmpl in a closure

i am working on this little javascript library and following various suggestions i am wrapping my functionality in a closure for the various reasons (encapsulation of variables, hidding of code and so on). since I query a JSON webservice and display the results I also use the jquery tmpl engine.
I think I understand what closures are good for but I sure don't understand them in general. meaning I get totally lost between all those scope changes and whatnot. especially annoying is this exception I get. consider the following code (a simplified ugly version of the code in question, but it reproduces the problem)
// something would be the object that handles all the library functionality
var something = function(){
// creating a local function that goes as a parameter into the Array.filter
function isBar(data){
return data.name === "bar";
}
// the template code
var bla = "<h1>${name}<\h1><h2>${attribute.filter(isBar)[0].value}</h2>";
// precompiling the the template
$.template("test", bla);
// and returning a function that should render the template with the provided data
return {
funny: function(){
$.tmpl("test", [{"name":"Fo", "attribute":[{"name":"bar", "value":"how"}]},
{"name":"Foo", "attribute":[{"name":"fnord","value":"can"}]},
{"name":"Fooo", "attribute":[{"name":"bar","value":"this"}]},
{"name":"Foooo", "attribute":[{"name":"Bar", "value":"be"}]}
]);
}
}
}();
// calling the function
something.funny();
So when calling the something.funny() I would the following expect to happen: the function funny, being a closure gets called in its original context (e.g. the function isBar and the variable bar are defined). So when I call $.tmpl I hoped that attribute.filter(isBar) within the template would also be in this scope. but it isn't. I Chrome i get ReferenceError: isBar is not defined.
If someone would be so nice to show me the error of my ways I would be very happy.
edit oops I missed the "()".
OK, well the problem is that those references to the local variables in the closure are not really references to local variables - they're part of a string. The template code has to parse that string, so when it does that the fact that there was a function called "isBar()" in the closure from where "$.tmpl()" was called really doesn't matter; jQuery can't access them because you just can't do that in JavaScript.
You can, however, pass in an "options" third parameter to "$.tmpl()" and provide extra stuff there. I'm not 100% sure how to do it as I've only played with the template plugin a little bit, but I'll try a jsfiddle when I have a chance. I think that you'd basically do something like this:
funny: function(){
$.tmpl("test", [{"name":"Fo", "attribute":[{"name":"bar", "value":"how"}]},
{"name":"Foo", "attribute":[{"name":"fnord","value":"can"}]},
{"name":"Fooo", "attribute":[{"name":"bar","value":"this"}]},
{"name":"Foooo", "attribute":[{"name":"Bar", "value":"be"}]}
], { isBar: isBar });
}
What I'm not sure of is whether you refer to that as "${isBar()}" or "${item.isBar()}" inside the template text.

How to isolate different javascript libraries on the same page?

Suppose we need to embed a widget in third party page. This widget might use jquery for instance so widget carries a jquery library with itself.
Suppose third party page also uses jquery but a different version.
How to prevent clash between them when embedding widgets? jquery.noConflict is not an option because it's required to call this method for the first jquery library which is loaded in the page and this means that third party website should call it. The idea is that third party site should not amend or do anything aside putting tag with a src to the widget in order to use it.
Also this is not the problem with jquery in particular - google closure library (even compiled) might be taken as an example.
What solutions are exist to isolate different javascript libraries aside from obvious iframe?
Maybe loading javascript as string and then eval (by using Function('code to eval'), not the eval('code to eval')) it in anonymous function might do the trick?
Actually, I think jQuery.noConflict is precisely what you want to use. If I understand its implementation correctly, your code should look like this:
(function () {
var my$;
// your copy of the minified jQuery source
my$ = jQuery.noConflict(true);
// your widget code, which should use my$ instead of $
}());
The call to noConflict will restore the global jQuery and $ objects to their former values.
Function(...) makes an eval inside your function, it isn't any better.
Why not use the iframe they provide a default sandboxing for third party content.
And for friendly ones you can share text data, between them and your page, using parent.postMessage for modern browser or the window.name hack for the olders.
I built a library to solve this very problem. I am not sure if it will help you of course, because the code still has to be aware of the problem and use the library in the first place, so it will help only if you are able to change your code to use the library.
The library in question is called Packages JS and can be downloaded and used for free as it is Open Source under a Creative Commons license.
It basically works by packaging code inside functions. From those functions you export those objects you want to expose to other packages. In the consumer packages you import these objects into your local namespace. It doesn't matter if someone else or indeed even you yourself use the same name multiple times because you can resolve the ambiguity.
Here is an example:
(file example/greeting.js)
Package("example.greeting", function() {
// Create a function hello...
function hello() {
return "Hello world!";
};
// ...then export it for use by other packages
Export(hello);
// You need to supply a name for anonymous functions...
Export("goodbye", function() {
return "Goodbye cruel world!";
});
});
(file example/ambiguity.js)
Package("example.ambiguity", function() {
// functions hello and goodbye are also in example.greeting, making it ambiguous which
// one is intended when using the unqualified name.
function hello() {
return "Hello ambiguity!";
};
function goodbye() {
return "Goodbye ambiguity!";
};
// export for use by other packages
Export(hello);
Export(goodbye);
});
(file example/ambiguitytest.js)
Package("example.ambiguitytest", ["example.ambiguity", "example.greeting"], function(hello, log) {
// Which hello did we get? The one from example.ambiguity or from example.greeting?
log().info(hello());
// We will get the first one found, so the one from example.ambiguity in this case.
// Use fully qualified names to resolve any ambiguities.
var goodbye1 = Import("example.greeting.goodbye");
var goodbye2 = Import("example.ambiguity.goodbye");
log().info(goodbye1());
log().info(goodbye2());
});
example/ambiguitytest.js uses two libraries that both export a function goodbye, but it can explicitly import the correct ones and assign them to local aliases to disambiguate between them.
To use jQuery in this way would mean 'packaging' jQuery by wrapping it's code in a call to Package and Exporting the objects that it now exposes to the global scope. It means changing the library a bit which may not be what you want but alas there is no way around that that I can see without resorting to iframes.
I am planning on including 'packaged' versions of popular libraries along in the download and jQuery is definitely on the list, but at the moment I only have a packaged version of Sizzle, jQuery's selector engine.
Instead of looking for methods like no conflict, you can very well call full URL of the Google API on jQuery so that it can work in the application.
<script src="myjquery.min.js"></script>
<script>window.myjQuery = window.jQuery.noConflict();</script>
...
<script src='...'></script> //another widget using an old versioned jquery
<script>
(function($){
//...
//now you can access your own jquery here, without conflict
})(window.myjQuery);
delete window.myjQuery;
</script>
Most important points:
call jQuery.noConflict() method IMMEDIATELY AFTER your own jquery and related plugins tags
store the result jquery to a global variable, with a name that has little chance to conflict or confuse
load your widget using the old versioned jquery;
followed up is your logic codes. using a closure to obtain a private $ for convience. The private $ will not conflict with other jquerys.
You'd better not forget to delete the global temp var.

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