jQuery post done and success

Question

jQuery documentation on jQuery post        Assign handlers immediately after making the request     and remember the jqxhr object for this request var jqxhr     post   example php   function       alert   success           done function         alert   second success             fail function         alert   error             always function         alert   finished             Perform other work here         Set another completion function for the request above jqxhr always function       alert   second finished           What is the difference between the success  parameter and the jqXHR done    method  if there is none  what is the entire point of the jqXHR done    method

User · Answer

The reason to prefer Promises over callback functions is to have multiple callbacks and to avoid the problems like Callback Hell.

Callback hell (for more details, refer http://callbackhell.com/): Asynchronous javascript, or javascript that uses callbacks, is hard to get right intuitively. A lot of code ends up looking like this:

asyncCall(function(err, data1){
    if(err) return callback(err);       
    anotherAsyncCall(function(err2, data2){
        if(err2) return calllback(err2);
        oneMoreAsyncCall(function(err3, data3){
            if(err3) return callback(err3);
            // are we done yet?
        });
    });
});

With Promises above code can be rewritten as below:

asyncCall()
.then(function(data1){
    // do something...
    return anotherAsyncCall();
})
.then(function(data2){
    // do something...  
    return oneMoreAsyncCall();    
})
.then(function(data3){
    // the third and final async response
})
.fail(function(err) {
    // handle any error resulting from any of the above calls    
})
.done();

User · Answer

Both  done   and  success   are callback functions and they essentially function the same way   Here s the documentation  The difference is that  success   is deprecated as of jQuery 1 8  You should use  done   instead   In case you don t want to click the link      Deprecation Notice      The jqXHR success    jqXHR error    and jqXHR complete   callback   methods introduced in jQuery 1 5 are deprecated as of jQuery 1 8  To   prepare your code for their eventual removal  use jqXHR done      jqXHR fail    and jqXHR always   instead

User · Answer

From the doc      jqXHR done function  data  textStatus  jqXHR             An alternative construct to the success callback option  the  done     method replaces the deprecated jqXHR success   method  Refer to   deferred done   for implementation details    The point it is just an alternative for success callback option  and jqXHR success   is deprecated

User · Answer

jQuery used to ONLY have the callback functions for success and error and complete     Then  they decided to support promises with the jqXHR object and that s when they added  done     fail     always    etc    in the spirit of the promise API   These new methods serve much the same purpose as the callbacks but in a different form   You can use whichever API style works better for your coding style   As people get more and more familiar with promises and as more and more async operations use that concept  I suspect that more and more people will move to the promise API over time  but in the meantime jQuery supports both   The  success   method has been deprecated in favor of the common promise object method names   From the jQuery doc  you can see how various promise methods relate to the callback types      jqXHR done function  data  textStatus  jqXHR        An alternative   construct to the success callback option  the  done   method replaces   the deprecated jqXHR success   method  Refer to deferred done   for   implementation details       jqXHR fail function  jqXHR  textStatus  errorThrown        An   alternative construct to the error callback option  the  fail   method   replaces the deprecated  error   method  Refer to deferred fail   for   implementation details       jqXHR always function  data jqXHR  textStatus  jqXHR errorThrown           An alternative construct to the complete callback option  the    always   method replaces the deprecated  complete   method       In response to a successful request  the function s arguments are the   same as those of  done    data  textStatus  and the jqXHR object  For   failed requests the arguments are the same as those of  fail    the   jqXHR object  textStatus  and errorThrown  Refer to deferred always     for implementation details       jqXHR then function  data  textStatus  jqXHR       function  jqXHR    textStatus  errorThrown        Incorporates the functionality of the    done   and  fail   methods  allowing  as of jQuery 1 8  the   underlying Promise to be manipulated  Refer to deferred then   for   implementation details    If you want to code in a way that is more compliant with the ES6 Promises standard  then of these four options you would only use  then

[jquery] jQuery.post( ) .done( ) and success:

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