Develop Reference

ajax call won't execute synchronously

I have built a weather website that calls the flickr API 1st, then calls the yahoo API for the weather. The problem is that the data from the ajax call - from the yahoo API is not here in time for the page to load its content.
Some of the things I have used to try and slow the ajax call down:
setTimeout
wrapping the entire function that $.ajax(success: ) calls into another function, wrapping it in setTimeout
taking the callback function out of $.ajax(success: ), and putting into the $.ajax(complete: ) param
taking the data object that $.ajax(success: ) passes in, and copying that to another var, then going outside of ajax call and putting the function that handles the data inside of $.ajaxComplete(), passing new object var
There are more ways that I have tried to go about this, but I have been at it for 3 days and cannot find a solution. Can someone please help me here
Here is a link to the project
My Weather App On codeine.io
function RunCALL(url)
{
var comeBack = $.ajax({
url: url,
async: false,
dataType:"jsonp",
crossDomain: true,
method: 'POST',
statusCode: {
404: function() {console.log("-4-4-4-4 WE GOT 404!");},
200: function() {console.log("-2-2-2-2 WE GOT 200!");}},
success: function(data){
weatherAndFlickrReport(data);},
error: function(e) {console.log(e);}
});
}

Are you using jQuery? If so, you have to chain your callbacks. Which, at a high level, would looks something like:
//You might want to use .get or .getJSON, it's up to what response you're expecting...
$.getJSON('https://example.com/api/flickr', function(response) {
//This your callback. The URL would end up being https://example.com/api/yahoo/?criteria=lalalalala
$.getJSON('https://example.com/api/yahoo/', { criteria: response.propertyYouWant}, function(yahooResponse) {
//Do something with your response here.
});
});
Edit: I have updated your snippet with a working solution (based on the above AJAX requests) which now shows both your JSON objects ready for consuming. Looky here.

Carry out Javascript/jQuery functions in a sequence

I want to make some wine. And my function does:
function wine(){
growGrapes();
process(grapes);
makeWine();
bottle();
}
However, Since my functions often consist of $.ajax() request, some other functions get carried out first. I have used the success tool, but it helps for one ajax request only.
success:function(result){
//Some Code
}
What I actually want is a sequence.
Literally, grapes get processed before growing them. What is a easiest approach?

jQuery Deferred Objects & Promises are the way to go. http://api.jquery.com/category/deferred-object/
They supports running multiple tasks in parallel or series using $.when(PassArrayOfPromisesToRunInParallel) to run processes in parallel and promise.then() to run items sequentially.

Call the next function in the success handler of the $.ajax call of the previous function!
Example:
function growGrapes(){
// lines of code
$.ajax({
success: function(result){
// call next function here - process(grapes); and so on...
}
});
}
The above makes sure the functions get called sequentially after the other..

You can make your Ajax calls synchronous (in sequence) by ensuring you have async: false in your $.ajax() settings.
For example:
$.ajax({ url: 'url',
async: false,
dataType: 'json',
success: function(data) {
}
});

First solution :
Make your ajax call syncronous by setting async : false when setting up your ajax call
$.ajax
({
async : false,
/* other settings */
});
Warning: This solution causes the UI to hand on intensive processing. This should never be used when doing anything rigorous on the server. My recommendation for using this is to only use it in checking flags or loading simple data.
Second solution :
As stated in the comments, use jQuery promises to set up the ordering. Here is a tutorial
I'll try to come back and provide a code example for this solution soon
Third solution :
Make your next call the success handler, or call the next step from the success handler
$.ajax
({
success : NextStep,
/* other settings */
})

One solution is to use queue() function. This way you can execute as many functions as you want
var ajaxQueue = $({});
$.ajaxQueue = function(ajaxOpts) {
// queue the method. a second call wont execute until this dequeues
ajaxQueue.queue(function(next) {
// for this example I serialize params, but you can save them in several variables
// and concat into ajaxOpts.data
var params = method_that_get_params_and_serialize_them();
ajaxOpts.data = params;
ajaxOpts.complete = function() {
next();
};
$.ajax(ajaxOpts);
});
};
then your functions should be like this:
function growGrapes(){
$.ajaxQueue({
cache: false,
type: "POST",
url: "someUrl",
dataType: "json",
data: "", // we fill data inside ajaxQueue() method
success: function( response) {
//do things with response
}
});
}

If you want to keep it tidy and clean to let people see how your calls are made, you can simply pass a callback function to another like this:
function growGrapes(callback) {
$.ajax({
...
success: function (){
// Something
if (typeof callback === typeof Function) callback();
},
...
});
}
function wine(){
growGrapes(function (){
process(grapes);
});
}

Sending an AJAX call before all other AJAX calls

I need to check for a condition and run an AJAX call before sending other AJAX calls on my web app.
I was thinking about putting this AJAX call in a beforeSend on ajaxSetup with async: false (to prevent my initial call from running before this one has completed).
Something like this:
//I set an event that fires:
$.ajax({
type: "GET",
url: my_url,
beforeSend: function() {
//do something, like show a spinner loader gif
}
});
//Somehwere in my app I also have:
$.ajaxSetup({
beforeSend: function() {
if(x===1){
$.ajax({
type: "GET",
url: my_url/fetch_something,
async:false
});
}
}
});
Will my beforeSend on the first AJAX call overrun the one in the ajaxSetup? Is there a way to approach this better?
Better idea of my app:
I have a lot of Ajax calls through the app, each call sends a security hash on the headers to validate the user, these hashes have a time limit as well (both hash and time limit are saved in localStorage)
What I want from ajax setup (and the condition in it) is to check for the time limit - if time_limit < current_time than run an ajax call to refresh the users hash.
This isn't an exercise for 1 or 2 calls, I literally have 20+ growing Ajax calls on my app that make use of the users hash and it's very impractical to make this check in every single one of them.

UPDATED:
Have one method on an interval that sets up the 'session'/local-storage
var refreshing = false;
var intervalID;
$(document).ready(function(e){
var delay = 1234;
intervalID = window.setInterval(setupInterval, delay);
});
function setupInterval(){
refreshing = true;
$.ajax(URL).done(function(r) { //do stuff
setupStorage(r);
refreshing = false;
});
}
function setupStorage(info){
//setup whatever here
}
OLD:
Could you use some logic in your ready function to gate what you need to do?
So basically call one ajax call -> if false, just schedule your latter methods, otherwise run the setup one and on completion schedule the latter method.
Some pseudo-code:
var refresh = false;
$(document).ready(function(e){
$.ajax(URL).done( function(r) {
if(r) {
routeOne();
} else {
latter();
}
});
});
function routeOne(){
$.ajax(URL).done(function(r) { //do stuff
latter();
});
}
function latter(){
//All other ajax calls
}
I'll put some more thought into this let me finish my coffee first...
EDIT:
Based on your updated description could it be possible for you to schedule a setInterval to run the checking method/hash update on the time interval that you need, and is the time interval on your server static or variable? Facebook does this with a heartbeat, I've used this type of logic with some 'locking' functionality in a web-app. If you schedule the interval properly it should not interrupt any other ajax calls.

Try overriding $.ajax to make a "pre-call" before passing in your given query options:
var oldAjax = $.ajax;
$.ajax = function() {
var args = arguments;
oldAjax({
type: "GET",
url: "/echo/html/",
success: function(result){
// do something here to check result
// if result is good, do the request:
return oldAjax.apply($, args);
// if its bad, handle the error
}
});
}
Here's a fiddle to demonstrate: http://jsfiddle.net/NF76U/

I suggest the use of .done() ( $.Deferred object)
function AjaxCall() {
return //code of your ajax without async:false
}
function anotherAjaxCall{
return //code of you ajax call
}
AjaxCall.done(anotherAjaxCall);
Avoid using async:false it's a deprecated practice and it stucks browsers

how to call a specific function on every ajax request

I have a problem, that I have several pages in my project and I used a lot of ajax requests in my project, but now I think that whenever an ajax request is called a function will called and whenever that request ends another function will call. How can I do this globally I know I can put this in every ajax request but I need a solution which I do in one place and it works all over the project.
$(document).read(function(){
// Suppose this document load function is written on layout page and every page is inherited from this page
});

Use ajaxSetup, for example
$.ajaxSetup({
beforeSend: function() {
console.log('test');
},
complete: function() {
console.log('completed');
}
});
will setup beforeSend handler for every ajax request. Note that ajaxSetup can take any option that $.ajax can.

You should create a wrapper function for your ajax, then use that function. that way, you have "central" control over the ajax call. something like:
//fast and crude way to extend jQuery
$.fn.customAjax = function(params){
//contains defaults and predefined functions
var defaults = {
complete : function(){...default complete hander...},
beforeSend : function (){...default beforeSend handler}
...
}
//merge settings
var finalParams = $.extend({},defaults,params);
//call ajax and return the deferred
return $.ajax(finalParams);
}
//use it like
$.customAjax({
url : ...,
method : ...,
data: ...,
complete : function(){...} //redefining in the call will override the defaults
});

.ajaxStart
Register a handler to be called when the first Ajax request begins.
.ajaxSucess
Attach a function to be executed whenever an Ajax request completes successfully.
for Detail doc:
http://api.jquery.com/category/ajax/

Try something like this:
$.ajax({
url: "test.html",
context: document.body
}).done(function() {
$.ajax({
url: "anotherMethod.html",
context: document.body
});
});
});
That means whenever ajax call completed successfully call your desire call.

It doesn't have a bug when complete. Click on Like, if work for you
$(document).ajaxSend(function(event, jqXHR, settings) {
$('#general-ajax-load ').fadeIn();
});
$(document).ajaxComplete(function(event, jqXHR, settings) {
$('#general-ajax-load ').fadeOut();
});

Using Javascript / JQuery to access an array built from an external XML file

I hope this is not too much of a newbe question but I've been pulling my hair out for a while now so thought I'd give in and ask for my first piece of advice on here.
I'm trying to read an external xml file using javascript / jQuery / ajax and place the retrieved data into an array so that I can then reference it later.
So far I seem to be doing everything right upto the point I put the data into the array but then I'm struggling to to read the data anywhere other than inside the function where I create it. Why am I not able to access the Array from anywhere other than in that function?
Here is my code...
Please help!!
$.ajax({
type: "GET",
url: "data.xml",
dataType: "xml",
success: do_xmlParser
});
function do_xmlParser(xml)
{
var myArray = new Array();
$(xml).find("tag").each(function ()
{
myArray.push($(this).find("innerTag").text());
});
console.log("inside "+myArray); // This outputs the array I am expecting
return myArray; // is this right???
}
console.log("outside: "+myArray); // This does NOT output the array but instead I get "myArray is not defined"

You're defining do_xmlParser as a callback to an asynchronous function (success of the jquery ajax call). Anything you want to happen after the ajax call succeeds has to occur within that callback function, or you have to chain functions from the success callback.
The way you have it now, the actual execution of code will go:
ajax -> file being requested -> console.log ->
file transfer done -> success handler
If you're doing some critical stuff and you want the call be to synchronous, you can supply the
async : false
setting to the ajax call. Then, you should be able to do something like this:
var myArray = [],
do_xmlParser = function (xml)
{
$(xml).find("tag").each(function ()
{
myArray.push($(this).find("innerTag").text());
});
};
$.ajax({
type: "GET",
url: "data.xml",
dataType: "xml",
success: do_xmlParser,
async: false
});
console.log("outside: " + myArray);
The async option doesn't work for cross-domain requests, though.
NOTE
I don't recommend doing this. AJAX calls are supposed to be asynchronous, and I always use the success callback to perform all of the processing on the returned data.
Edit:
Also, if you're into reading... I'd recommend jQuery Pocket Reference and JavaScript: The Definitive Guide (both by David Flanagan).

look close and you will see. You are actually firing up an array that dosen't exist. You have declared myArray inside function. Try do something like this.
console.lod("outside :"+do_xmlParser(xml)); // I think that when you merge a string and an array it will output only string, but I can be wrong.