I would like to ask if there is a liveconnect equivalent for ActionScript 3. I understand that there is the ExternalInterface class inside AS3 but it only supports calling a method by name. The really cool thing about Java and LiveConnect is that you can do something like
function jsFunc(name) = {
this.name = name;
this.talk = function(){
alert('hello world my name is ' + this.name);
}
}
javaapplet.function(new jsFunc("bob"));
The above approaches pseudo code since I never tested it but I've seen it in action. In AS3, while I am able to pass in an instance of JavaScript "object" into AS, it is often converted into an ActionScript Object instance which does away with all the functions as far as I'm aware.
I saw an implementation of JSInterface but I don't think it does specifically that. Is there any way to make OO like javascript work with ActionScript 3?
Try this library on Google code:
http://code.google.com/p/jsobject/
ExternalInterface.call("f = function() { alert('Is this like live connect?'); }");
Actually the main usage scenario is to have JS "objects" interacting with the Flex SWF application. Therefore when the JS "object" wants to say wait for something happening in the SWF object, it will put in a "this" with a callback.
After researching, the way I used to accomplish this is via the Flex Ajax bridge. It may not be a direct answer to the way I phrased the question but it was sufficient for my needs.
Basically what I do is via FABridge, after initializing, I'll attach event listeners to the object.
// JS
FlexApp.addEventListeners('flexDidSomething', this.doSomething().bind(this)); //using mootools;
and in Flex, the main application itself
// AS
dispatchEvent(new CustomCreatedEvent(param1, param2));
And inside the JS function I'll access the get methods of the event object to retrieve the params.
There's tight coupling in that sense but it works at least for what I need.
Hope this is helpful!
JSInterface designed exactly for such things.
Related
I've learnt development by looking at other people's codes, so I'm not very good with terminologies. Lately I've been writting my JS/Jquery this way:
$(document).ready(function() {
testingFunc.init();
});
var testingFunc = {
$object: $('#object'),
init: function() {
var _that = this;
console.log($object);
}
}
Can someone please tell me if this a pattern of some sort? Or can someone please tell me how to describe the code I've done above?
This particular style represented in your code is an "object literal" pattern. It differs only slightly from a "module" pattern when you find yourself not requiring specific properties or methods to be private.
Before getting into a trap of terminologies, you may want to understand (in principle) what Javascript patterns are, and then identify those which may be architecturally best-fit for your project.
You may get an in-depth understanding from this mini-book from Addy Osmani:
http://addyosmani.com/resources/essentialjsdesignpatterns/book/
And a high-level article from him:
http://addyosmani.com/largescalejavascript/
The first part is using a jQuery selector with the listener "ready". What this means is that the callback function attached to the selector and listener will run once the document (in this case the browser window) is ready (in web terms, this means when the page finishes loading).
The second part of your code is following a standard called object literal, which is a JavaScript methodology that follows the principles of key->value
Perhaps you can name it the Object Literal pattern like used by Rebecca Murphey in her article. However I do not think that it's widely adopted as an official name for this kind of code structure, but it seems appropriate.
I guess you are wondering about the ready function. In order to understand how it works, you have to know that when you load an HTML page into you browser, the HTML structure is turned into a javascript tree called "DOM" (Document Object Model). In your sample, the DOM is referenced through the variable named document. To populate this tree, each markup has to be initialized as a javascript object. Once this job is done, the "ready" event is raised, invoking every function which is bound to it. To summarize :
$(document).ready(function () { testingFunc.init(); });
// translation : Once the DOM has been initialized, call "init".
Regarding your code, $('#object') attempts to query the DOM tree to find a node with an id set to "object" (e.g. <div id="object">). However, the document is probably not yet fully initialized. As a result, this query might fail. To avoid this risk you should rather do this :
var testingFunc = {
$object: null,
init: function() {
this.$object = $('#object');
console.log(this.$object);
}
}
You can think of the DOM as a folder structure, where each folder and file is an HTML markup. jQuery browses the DOM tree the same way that you browse your files explorer.
I'm not sure this is supported but wanted to see if any of you had come up with something creative to work around this.
Is there a way to call javascript from silverlight, without having to define any javascript functions on the aspx page/external js?
I'd like to be able to do something like:
HtmlPage.Window.Invoke("(function () { window.lastErrorMessage = 'foo'; })();")
Which, to forgo conversations about style, I'd agree goes against many best practices rules, but my current purpose is brainstorm some quick-and-dirty error reporting (could you even call it reporting?) before we implement the existing database-centric error logging in this solution.
Any thoughts? The idea is to generate something discreet that a user wouldn't feel intruded upon or something too technical (like IE's script error dialog), but something our app support could get a little more info from without access to code bases etc.
Thanks, Matthew
The method you are looking for is Eval not Invoke:-
HtmlPage.Window.Eval("(function () { window.lastErrorMessage = 'foo'; })();")
You could add your JavaScript dynamically to the hosting page DOM using HtmlPage.Document and then execute your added methods. Or are you trying not to modify the page at all?
HtmlElement head = HtmlPage.Document.GetElementsByTagName("head")[0] as HtmlElement;
HtmlDocument htmlDocument = HtmlPage.Document;
HtmlElement scriptElement = htmlDocument.CreateElement("script");
scriptElement.SetAttribute("type", #"text/javascript");
scriptElement.SetProperty("text", "function testMe(p) { alert(p); }");
head.AppendChild(scriptElement);
// Invoke like this
HtmlPage.Window.Invoke("testMe", "hello");
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.
Most of the examples you find on the web, of using javascript from ASP.NET pages puts the javascript in the markup file (*.aspx). This is, of course, a really bad idea(tm), for all but the simplest uses of javascript.
What we want, of course, is to wrap the javascript up into a class, and to instantiate an instance of that class and tie it to the code-behind.
Microsoft provides a framework for doing this for user controls and server controls, in its IScriptControl interface. This allows a developer to create a javascript "component" - to define a javascript class in a *.js file, to include the *.js file on the page that contains the control, to instantiate an instance of the component, to set variables in the component from values in the code-behind, and to get a reference to the component in javascript on the client side.
The thing is - IScriptControl only works for user and server controls. It cannot be used to instantiate javascript objects at the page level.
So - how do people do this? We have some patterns we've been using, that seem to work. I was wondering what everyone thought of them, and what other people were using.
We start by defining a javascript class in a *.js file. In the code-behind, we create a loadJavascript() function, that we call from Page_Load on initial load or full postback (but not on partial postbacks).
In loadJavascript(), we include the *.js file with ScriptManager.RegisterClientScriptInclude(), and then construct a bit of javascript that instantiates an instance of the class, assigns a reference to a known name, and registers the object's initialize() and dispose() methods as handlers for window.load and window.unload.
E.g.:
string url = this.ResolveUrl("./FooBar.js");
ScriptManager.RegisterClientScriptInclude(this, this.GetType(), url, url);
string script = #"
if (typeof {0}_obj == 'undefined')
{0}_obj = {{}};
{0}_obj.fooBar = new FooBar();
Sys.UI.DomEvent.addHandler(window, 'load',
function()
{{
{0}_obj.fooBar.initialize('{1}', '{2}');
}}
);
Sys.UI.DomEvent.addHandler(window, 'unload', {0}_obj.fooBar.dispose);
";
script = String.Format(script,
new object[]
{
this.ClientID,
this.foo.ClientID,
this.bar.ClientID
});
ScriptManager.RegisterStartupScript(
this, this.GetType(), this.ClientID, script, true);
We construct an object name in the global namespace, based on the ClientID of the page, if we haven't already. We add an instance of our new class as a member of our global object. We add a window.load handler that calls our object's intialize() method, passing the clientIDs of the controls on the page that the object's methods need to access. And we add a window.unload handler that calls our object's dispose() method, that does whatever cleanup that is necessary.
This seems to be working, for us. We've used this pattern on a number of pages, some of which did significant amounts of partial-postbacks, without any problems.
I was wondering, first, what people thought of the pattern.
But more, I was wondering if we'd been reinventing the wheel, and if there were other approaches to dealing with the issues we were addressing, that we weren't aware of.
Anyone have any better ideas?
But more, I was wondering if we'd been reinventing the wheel, and if there were other approaches to dealing with the issues we were addressing, that we weren't aware of.
I think this the most good approaches, I use the same way some years now with out any problem in very complex javascript code. I do not see why you question your self :)
The idea is this you follow, now maybe there are some variations, maybe I not call the unload, nether create an object to keep the foobar and call the foobar rightway, but the idea is the same. I also check if the Javascript file have been loaded...
string script = #"
if (typeof (FooBar) != "undefined") {{
var {0}fooBar = new FooBar();
Sys.UI.DomEvent.addHandler(window, 'load',
function()
{{
{0}fooBar.initialize('{1}', '{2}');
}}
);
}}
i've been playing with MVC for a while now, but since the project i'm on is starting to get wind in its sails more and more people are added to it. Since i'm in charge of hacking around to find out some "best practice", i'm especially wary about the possible misuses of javascript and would like to find out what would be the best way to have our views and partial views play nicely with javascript.
For the moment, we're having code that looks like this (only simplified for example's sake)
<script type="text/javascript">
function DisableInputsForSubmit() {
if ($('#IsDisabled').is(':checked')) {
$('#Parameters :input').attr('disabled', true);
} else {
$('#Parameters :input').removeAttr('disabled');
}
}
</script>
<%=Html.SubmitButton("submit", Html.ResourceText("submit"), New With {.class = "button", .onclick = "DisableInputsForSubmit(); if ($('#EditParameters').validate().form()) {SetContentArea(GetHtmlDisplay('SaveParameters', 'Area', 'Controller'), $('#Parameters').serialize());} return false;"})%><%=Html.ResourceIcon("Save")%>
Here, we're saving a form and posting it to the server, but we disable inputs we don't want to validate if a checkbox is checked.
a bit of context
Please ignore the Html.Resource* bits, it's the resource management
helpers
The SetContentArea method wraps ajax calls, and GetHtmlDisplay
resolves url regarding an area,
controller and action
We've got combres installed that takes care of compressing, minifying
and serving third-parties libraries and what i've clearly identified as reusable javascript
My problem is that if somebody else defines a function DisableInputsForSubmit at another level (let's say the master page, or in another javascript file), problems may arise.
Lots of videos on the web (Resig on the design of jQuery, or Douglas Crockford for his talk at Google about the good parts of javascript) talk about using the namespaces in your libraries/frameworks.
So far so good, but in this case, it looks a bit overkill. What is the recommended way to go? Should i:
Create a whole framework inside a namespace, and reference it globally in the application? Looks like a lot of work for something so tiny as this method
Create a skeleton framework, and use local javascript in my views/partials, eventually promoting parts of the inline javascript to framework status, depending on the usage we have? In this case, how can i cleanly isolate the inline javascript from other views/partials?
Don't worry and rely on UI testing to catch the problem if it ever happens?
As a matter of fact, i think that even the JS code i've written that is in a separate file will benefit from your answers :)
As a matter of safety/best practice, you should always use the module pattern. If you also use event handlers rather than shoving javascript into the onclick attribute, you don't have to worry about naming conflicts and your js is easier to read:
<script type="text/javascript">
(function() {
// your button selector may be different
$("input[type='submit'].button").click(function(ev) {
DisableInputsForSubmit();
if ($('#EditParameters').validate().form()) {
SetContentArea(GetHtmlDisplay('SaveParameters', 'Area','Controller'), $('#Parameters').serialize());
}
ev.preventDefault();
});
function DisableInputsForSubmit() {
if ($('#IsDisabled').is(':checked')) {
$('#Parameters :input').attr('disabled', true);
} else {
$('#Parameters :input').removeAttr('disabled');
}
}
})();
</script>
This is trivially easy to extract into an external file if you decide to.
Edit in response to comment:
To make a function re-usable, I would just use a namespace, yes. Something like this:
(function() {
MyNS = MyNS || {};
MyNS.DisableInputsForSubmit = function() {
//yada yada
}
})();