callback
How can I run a JavaScript callback when an image is loaded?
.complete + callback This is a standards compliant method without extra dependencies, and waits no longer than necessary: var img = document.querySelector(‘img’) function loaded() { alert(‘loaded’) } if (img.complete) { loaded() } else { img.addEventListener(‘load’, loaded) img.addEventListener(‘error’, function() { alert(‘error’) }) } Source: http://www.html5rocks.com/en/tutorials/es6/promises/
jQuery: Handle fallback for failed AJAX Request
You will need to either use the lower level $.ajax call, or the ajaxError function. Here it is with the $.ajax method: function update() { $.ajax({ type: ‘GET’, dataType: ‘json’, url: url, timeout: 5000, success: function(data, textStatus ){ alert(‘request successful’); }, fail: function(xhr, textStatus, errorThrown){ alert(‘request failed’); } }); } EDIT I added a timeout … Read more
Extracting Ajax return data in jQuery
You can use .filter on a jQuery object that was created from the response: success: function(data){ //Create jQuery object from the response HTML. var $response=$(data); //Query the jQuery object for the values var oneval = $response.filter(‘#one’).text(); var subval = $response.filter(‘#sub’).text(); }
Java pattern for nested callbacks?
Since the implementation (not only the interface) must not block, I like your list idea. Set up a list of “operations” (perhaps Futures?), for which the setup should be pretty clear and readable. Then upon receiving each response, the next operation should be invoked. With a little imagination, this sounds like the chain of responsibility. … Read more
How to refactor Node.js code that uses fs.readFileSync() into using fs.readFile()?
var fs = require(“fs”); var filename = “./index.html”; function start(resp) { resp.writeHead(200, { “Content-Type”: “text/html” }); fs.readFile(filename, “utf8”, function(err, data) { if (err) throw err; resp.write(data); resp.end(); }); }
What is the difference between Page.IsPostBack and Page.IsCallBack?
Page.IsCallBack It is getting a value indicating whether the page request is the result of a call back. Its a special postback, so a round-trip always occurs; however, unlike the classic postback, the script callback doesn’t redraw the whole page. ViewState is not updated during a callback, it is for postback. Page.IsPostBack Checks whether the … Read more
Mixing C functions in an Objective-C class
Mixing C and Objective-C methods and function is possible, here is a simple example that uses the SQLite API within an iPhone App: (course site) Download the Zip file (09_MySQLiteTableView.zip) C functions need to be declared outside of the @implementation in an Objective-C (.m) file. int MyCFunction(int num, void *data) { //code here… } @implementation … Read more
What steps do I need to take to use WCF Callbacks?
Here is about the simplest complete example that I can come up with: public interface IMyContractCallback { [OperationContract] void OnCallback(); } [ServiceContract(CallbackContract = typeof(IMyContractCallback))] public interface IMyContract { [OperationContract] void DoSomething(); } [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant)] public class MyService : IMyContract { public void DoSomething() { Console.WriteLine(“Hi from server!”); var callback = OperationContext.Current.GetCallbackChannel<IMyContractCallback>(); callback.OnCallback(); } } … Read more
How can a Windows service application be written in Haskell?
I admit, this problem has been vexing me for some days now. From walking the return values and the contents of GetLastError, I’ve determined that this code should be working correctly according to the system. Because it clearly isn’t (it seems to enter an undefined state that inhibits the service handler from running successfully), I’ve … Read more