JSONP only working with named callback function - javascript

I have gotten JSONP working with an anonymous function but can't get it to work with a named function. This code works (the alert appears with the correct data):
$.getJSON('http://example.com/test.aspx?foo=bar&callback=?',
function (data) { alert(data.baz) })
However this code does not work (no alert appears):
function dat(data) {
alert(data.baz)
}
$.getJSON('http://example.com/test.aspx?foo=bar&callback=dat')
Can you explain why the last code does not work?
EDIT: I took out a non-relevant example

I'm not sure that leaving out the callback is the correct usage (or, at least, I cannot find any documentation that defines what should happen if a callback is not supplied). If you want to use a named function as the callback you can do:
function dat(data) {
alert(data.baz)
}
$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', dat);

You should be able to meet jQuery half way with something like this:
$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', dat);

After looking at jquery's ajax code a bit, I think what you want to do is either
do like Dave Ward and Hamish suggest, ie pass in the function. Or, I think you can pass the function's name as a string like this, since it is attached to the window and jquery looks at the type of the callback for determining behavior.
function dat(data) {
alert(data.baz)
}
$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', 'dat');
Or, you can use getScript which will add the url as a script tag, which is fine for what you are trying to do.
function dat(data) {
alert(data.baz)
}
$.getScript('http://example.com/test.aspx?foo=bar&callback=dat');

Related

jQuery (or clean JS) - add callback to any function-parameter

What I want looks like this:
function bindFunctions(bindFunction, callbackFunction) {
// Add binding so that I can call the callbackFunction if the bindFunction is called
}
function log(message) {
console.log(message);
}
function notifyUser() {
alert('Something');
}
bindFunctions(log, notifyUser);
log('Error'); // Now the notifyUser-functions should be called and "Something" printed to the alert-box
bindFunctions($('.element').click, function() {/* CODE */}); // Or this: but I don't know if this is even possible because this is not the event-function but the binding-function of the click-event
Important: I have no influence on the bindFunction so it's not possible to implement a trigger there.
It's an attachment of a callback on any kind of existing function. Do you know how or if this is possible?
I believe you're looking at it the wrong way. What you need is some good old dependency inversion. Whatever code needs log has to receive it from a higher-level component (e.g. the composition root of your application). You're then free to implement a straightforward wrapper that calls notifyUser and inject it instead of the actual log.
I've linked some articles taking an OO perspective, but feel free to translate to a more functional model (the approaches are equivalent). In your case, you're using closures (which are, under a certain light, "equivalent" to objects with a single anonymous method).
The way you have to do to add a callback to a function is this:
var foo = function(number, callback){
number += 2;
callback(number);
}
foo(2, function(result){
window.alert(result)
});
https://jsfiddle.net/6dpz88md/
Good luck

JavaScript function returns undefined except when debugging

When trying this simple code:
function create_folder(name, parent_ID) {
var BM_folder = "";
chrome.bookmarks.create({title : name, parent_id : parent_ID }, function (new_folder) {
BM_folder = new_folder;
});
console.log("create folder in id : " + BM_folder.id);
return BM_folder.id;
}
I get undefined as output, but when I debug it works fine and I get the real bookmark ID. I have similar problems in more functions, I guess it's the same problem.
EDIT #1: fixed the vars, my real function has full strings, I simply can't post that way.
EDIT #2: thanks Marco Bonelli, is there a way to turn this into sync, so that I'll be able to use normal oop?
There are several problems in your code:
First of all, that function cannot work... you're using a hypen (-), and variable/function names cannot contain hypens in JavaScript, so change it in something else, maybe create_folder or createFolder. That's the same for your variable BM-folder, and parent-ID. Call them BMFolder and parentID.
Secondly, you are creating the object to pass to chrome.bookmarks.create() in the wrong way: parent-ID is both wrong and undefined. You should do: chrome.bookmarks.create({title: name, parentID: parentid}).
Inside your function, you're calling the chrome.bookmarks.create() method, which is asynchronous: this means that the code is processed separately from the body of your function, and when the method has finished working, it will call the callback function, which you provide as second argument. Basically when calling chrome.bookmarks.create() you have to wait until it's finished to continue, because if you try to access the BMfolder.id variable before the callback gets called it will obviously be undefined.
Now, to summarize what I said above, I'll show the right code for to achieve you're trying to:
function createFolder(name, parentid) {
chrome.bookmarks.create({title: name, parentID: parentid }, function (newFolder) {
console.log("Created the folder with ID: " + newFolder.id);
goOn(newFolder);
});
}
function goOn(BMFolder) {
console.log('Here is the folder: ', BMFolder);
// do something...
}
You cannot use return BMFolder.id, because your function is asynchronous, so the only thing you can do to know that the bookmark folder has been created is to call another function to continue. For example, you can name it goOn().
EDIT:
Is there a way to turn this into sync, so that I'll be able to use normal oop?
Unfortunately you cannot turn an asynchronous function into a synchronous one. Chrome extensions' methods are only asynchronous, therefore you have to work on that. By the way, working asynchronously is much more efficient than working synchronously, and you should get used to this programming style, because (as said before) Chrome extensions only work asynchronously, and so do many other JS frameworks and APIs.

How does this javascript work?

I'm a javascript noob, and I don't understand why this works:
$().load('/my/url/', {my:data, more:data}, jsFunc());
function jsFunc()
{
$("#myid").val("yep");
}
But not this:
$().load('/my/url/', {my:data, more:data}, function() {jsFunc()});
function jsFunc()
{
$("#myid").val("yep");
}
I tried an $.ajax instead of $.load with the same result. I will be passing the response data to jsFunc() and that is why I need jsFunc() inside the function. I'm sure it is something simple I'm just not very experienced with javascript. Thanks.
Thanks again for all the help. I decided to use $.post because it works best for the situation but now I'm having trouble with the response data. My code looks like this:
$.post('/my/url/', {my:data, more:data}, function(data) {
var strung = JSON.stringify(data)
var parse = jQuery.parseJSON(strung)
console.log(parse.some);}, 'json');
I'm logging to the console to see what is coming back for now and I will add the callback when I see the correct value logged. The process I got from the jQuery api page, but it will only log undefined. When I change parse.some to parse the console log will display the objects and I can select an element and see the correct key:value pair. Any help would be sweet.
Neither works. The first one appears to work, because you call the function jsFunc immediately, it doesn't wait for any response.
If you create an empty jQuery object using $() and use the load method on that, it won't call the server because there is no element where it can put the result.
To specify the callback function you either use the name of a function:
$('#someElement').load('/my/url/', {my:data, more:data}, jsFunc);
or a function expression:
$('#someElement').load('/my/url/', {my:data, more:data}, function() { jsFunc(); });
The first code block will simply call jsFunc() and return the results as the parameter to the load(..) method, which is odd because that parameter is supposed to be a callback function to fire when the load completes, but that works? The callback syntax is more in keeping with the second example (the one I believe you stated doesn't work).
Answer to my second part:
My returned JSON data consisted of many objects, so I had to specify the index and the key to get the value to return.

Get jquery selector from object parameter

box_tpv1 = {
box:$("#box_tpv1"),
open:function(mensaje,f_ok,f_x){
this.box.show()
}
}
And when I call this box_tpv1.open() won't work, but If I write inside open function $("#box_tpv1").show() it works.
In your case, box_tpv1 is a singleton object, which cannot be further instantiated using new. Which means the value of this is insignificant.
You might as well simply call box_tpv1.box.show() inside the open function.
there might be issues on the context this function is being called and that depends upon from where are you calling this function from
try calling like this
box_tpv1.open.call(box_tpv1);
I don't know why but I solved it this way, I can get with this.box the value inside the object methods but doesnt work the jquery selector, if I do that it works
box_tpv1 = {
box:"#box_tpv1",
open:function(mensaje,f_ok,f_x){
$(this.box).show()
}
}

Pass a callback in ExternalInterface

I want to call a Javascript function from Flash, which I can do with ExternalInterface, but the Javascript function takes a callback. Is there a way to give it a Flash callback?
I've thought of something like this:
ExternalInterface.addCallback("foo", function(){...});
ExternalInterface.call("theFunction", "foo");
But that wouldn't work since theFunction would attempt to do foo(), while it should really do swfObject.foo(). The problem is the page and its Javascript are not under my control (though I can request changes if really needed).
This is closely related to the first question in the related questions section.
Along the same lines as the answer to that question, you can do:
ExternalInterface.addCallback("foo", function() { /* ... */ }); // The callback
ExternalInterface.call("theFunction(function() { swfObject.foo(); })");
You're misunderstanding the documentation, I think. callback in this instance is just a reference to a function inside Flash, not a callback to something you call.
Basically, you use .call() to call a JS function from AS; and you use .addCallback() to tell the Flash Player which AS function should be called based on the name.
On your example, theFunction would get one parameter as being 'foo', which is the name that references your anonymous AS function. Not sure why you would want to pass the function like that, but if you need, you could just call it from JavaScript with
function theFunction(callback) {
// .. do something...
swfObject[callback]();
}
Now, if you don't have control over the JS/HTML side, I'm not sure if you can do that. Not sure why you'd need, anyway - JS calls are synchronous, as if they were running on the same thread, meaning the Flash Player will execute the JS code and only then return to the Flash Player... you don't have to wait for execution or anything.
Also, if you really need to control the page without touching the JS/HTML side, remember you can inject entire pieces of JS code via .call - it doesn't need to be a simple function call. You can create your entire functions from inside the SWF. For example,
var js:XML = <script><![CDATA[
// Javascript code...
]]></script>;
ExternalInterface.call(js);
Or, if you need the return data, you don't need a callback either - just do a simple call as in
// JS
function isNumberZero(__num) {
return __num == 0;
}
// AS
trace ("Is number zero = " + ExternalInterface.call("isNumberZero", 10));
Not sure if this helps at all. If not, it'd be good to have more information on what exactly you're trying to do.

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