I have a jQuery file which also uses unserscore.js. It controls the selections of dates and different venues. For one of the pages it also controls which visuals are displayed depending on the type of venue. I can successfully, using ajax, get the type of page, but I have been unable to pass that value to a public variable in the script. It is based on which WiFi spot the data is coming from. If the data is from a local spot the page should display a d3 bubble chart. If it's from a remote spot it should display a map of the venue. Currently I have the functionality working with hard coding based on the id of the venue which is far from ideal.In order to make the decision based on which spot the venue is using I created an ajax call that gets the "spot". With console.log I can see that I am getting the correct result from the ajax call, but I'm missing something in terms of passing that information to a variable so I can use it.
This is the complete jQuery files:
define([
"ui/selects",
], function (SelectsUiClass) {
var global = this;
var MainControlsClass = function () {
// Private vars
var _this = this,
_xhr = null,
_selects = new SelectsUiClass(),
_dateRangeSelect,
_venueSelect,
_floorSelect,
_zoneSelect;
// Public vars
this.Selects = null;
this.spotName = null;
// Private Methods
var _construct = function () {
_dateRangeSelect = _selects.InitSelect('#mainControls-dateRange', _onSelectChange);
_venueSelect = _selects.InitSelect('#mainControls-venue', _onSelectChange);
_floorSelect = _selects.InitSelect('#mainControls-floor', _onSelectChange);
_zoneSelect = _selects.InitSelect('#mainControls-zone', _onSelectChange);
var value = _this.GetVenue();
_getChartDisplayDiv(value);
};
var _getChartDisplayDiv = function (venueId) {
var path = window.location.pathname,
pathArray = path.split("/"),
page = pathArray[pathArray.length - 1];
console.log('controlsjs 36, navigation page: ' , page);
console.log('controlsjs 37, venue value: ' , venueId);
_this.Load(venueId);
console.log('Controls 40, sPot Name = ', _this.spotName);
if (page === 'heatmap') {
if (venueId === 8 || venueId === 354) {
//make the bubble div visible
$("#heatmap-bubble").show();
//make the map div invisible
$("#heatmap-map").hide();
} else {
//make the map div visible
$("#heatmap-map").show();
//make the bubble div invisible
$("#heatmap-bubble").hide();
}
}
}
this.Load = function (venueId) {
console.log("Controls 66, Venue Id sent = ", venueId);
if (_xhr) {
_xhr.abort();
_xhr = null;
}
_this.SetLoading(true);
_xhr = $.ajax({
url: $("meta[name='root']").attr("content") + '/app/heatmap/spot',
type: 'POST',
headers: {
'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
},
data: {
venue_id: venueId
},
dataType: 'JSON',
async: true,
cache: false,
error: function (jqXHR, textStatus, errorThrown) {
_this.SetLoading(false);
},
success: function (response) {
_this.SetLoading(false);
console.log("Controls 90, Response of ajax call = ", response);
_this.Update(response);
}
});
};
// Public functions
this.SetLoading = function (option) {
if (_.isUndefined(option)) { option = false; }
if (this.spotName) { this.spotName.SetLoading(option); }
};
this.Update = function (data) {
if (_.isUndefined(data) || _.isNull(data)) {
console.log('Controls 106: Spot Name: ', data)
this.spotName = data;
}
};
var _getVenueData = function (venueId) {
for (var i = 0; i < venuesData.length; i++) {
if (venuesData[i].id === venueId) {
if (!_.isUndefined(venuesData[i].spot_data)) {
return venuesData[i].spot_data;
}
}
}
};
var _onVenueChange = function () {
var value = _this.GetVenue();
if (_.isNull(value)) {
return;
}
_getChartDisplayDiv(value);
//_setSelectValue(_venueSelect, value);
var venueData = _getVenueData(value);
console.log('Venue data received: ', venueData);
if (!_.isUndefined(venueData) && !_.isUndefined(venueData.floors)) {
_selects.UpdateSelect(_floorSelect, venueData.floors);
_onFloorChange();
}
};
var _onFloorChange = function () {
var value = _this.GetFloor(),
zones = [];
if (_.isNull(value)) {
return;
}
//_setSelectValue(_floorSelect, value);
if (_.isNumber(value)) {
var venueData = _getVenueData(_this.GetVenue()),
floors = venueData.floors;
for (var i = 0; i < floors.length; i++) {
if (floors[i].id === value) {
zones = floors[i].zones;
}
}
}
_selects.UpdateSelect(_zoneSelect, zones);
};
var _onZoneChange = function () {
var value = _this.GetZone();
if (_.isNull(value)) {
return;
}
//_setSelectValue(_zoneSelect, value);
};
var _onSelectChange = function (e) {
var t = $(e.target),
id = t.attr('id');
if (_venueSelect && _venueSelect.attr('id') === id) {
_onVenueChange();
} else if (_floorSelect && _floorSelect.attr('id') === id) {
_onFloorChange();
} else if (_zoneSelect && _zoneSelect.attr('id') === id) {
_onZoneChange();
}
EventDispatcher.Dispatch('Main.Controls.Change', _this, {
caller: id
});
};
// Public Methods
this.GetDateRange = function () {
return _selects.GetSelectValue(_dateRangeSelect);
};
this.GetDateRangeKey = function () {
if (_dateRangeSelect) {
var selected = _dateRangeSelect.find('option:selected');
if (selected.length) {
return selected.attr("data-key") || "";
}
}
return "";
};
this.GetVenue = function () {
return _selects.GetSelectValue(_venueSelect);
};
this.SetVenue = function (value) {
_selects.SetSelectValue(_venueSelect, value);
}
this.GetFloor = function () {
return _selects.GetSelectValue(_floorSelect);
};
this.SetFloor = function (value) {
_selects.SetSelectValue(_floorSelect, value);
}
this.GetZone = function () {
return _selects.GetSelectValue(_zoneSelect);
};
this.SetZone = function (value) {
_selects.SetSelectValue(_zoneSelect, value);
}
this.GetData = function () {
return {
dateRange: {
date: this.GetDateRange(),
key: this.GetDateRangeKey()
},
venue: this.GetVenue(),
floor: this.GetFloor(),
zone: this.GetZone()
};
};
// Init
_construct();
};
return MainControlsClass;
});
The function that determines which visual to display is close to the top: _getChartDisplayDiv:
var _getChartDisplayDiv = function (venueId) {
var path = window.location.pathname,
pathArray = path.split("/"),
page = pathArray[pathArray.length - 1];
_this.Load(venueId);
console.log('Controls 40, sPot Name = ', _this.spotName);
if (page === 'heatmap') {
if (venueId === 8 || venueId === 354) {
//make the bubble div visible
$("#heatmap-bubble").show();
//make the map div invisible
$("#heatmap-map").hide();
} else {
//make the map div visible
$("#heatmap-map").show();
//make the bubble div invisible
$("#heatmap-bubble").hide();
}
}
}
When I am able to pass the "spot" information to it or a variable that it uses, it should look like this:
var _getChartDisplayDiv = function (venueId) {
var path = window.location.pathname,
pathArray = path.split("/"),
page = pathArray[pathArray.length - 1];
_this.Load(venueId);
console.log('Controls 40, sPot Name = ', _this.spotName);
if (page === 'heatmap') {
if (_this.spotName === 'local' ) {
//make the bubble div visible
$("#heatmap-bubble").show();
//make the map div invisible
$("#heatmap-map").hide();
} else {
//make the map div visible
$("#heatmap-map").show();
//make the bubble div invisible
$("#heatmap-bubble").hide();
}
}
}
My ajax call is here:
this.Load = function (venueId) {
console.log("Controls 66, Venue Id sent = ", venueId);
if (_xhr) {
_xhr.abort();
_xhr = null;
}
_this.SetLoading(true);
_xhr = $.ajax({
url: $("meta[name='root']").attr("content") + '/app/heatmap/spot',
type: 'POST',
headers: {
'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
},
data: {
venue_id: venueId
},
dataType: 'JSON',
async: true,
cache: false,
error: function (jqXHR, textStatus, errorThrown) {
_this.SetLoading(false);
},
success: function (response) {
_this.SetLoading(false);
console.log("Controls 90, Response of ajax call = ", response);
_this.Update(response);
}
});
};
This successfully gets the right spot, but I have been unable to pass it to a variable I can use. I think I am getting mixed up between private and public variables. I tried to use the 'this.Update' function to pass the setting to the public 'this.spotName' variable, but that comes up null. I have also tried to simply return the result of the ajax call, but I get a "not a function" error. How can I make the result of the ajax call available to my '_getChartDisplayDiv' function?
Your problem is that you are trying to read the value of _this.spotName before it is assigned. Let us walk through the steps that happen.
When you call _getChartDisplayDiv(value), the _getChartDisplayDiv function first calls _this.Load(venueId). Load, in turn, submits an ajax request with a success callback, reproduced in abbreviated form below:
this.Load = function (venueId) {
// ...
_this.SetLoading(true);
_xhr = $.ajax({
...
success: function (response) {
_this.SetLoading(false);
console.log("Controls 90, Response of ajax call = ", response);
_this.Update(response);
}
});
};
When the response arrives, the success callback will be invoked, which in turn will call _this.Update, which will set the variable you are after. The syntax you used for this purpose is correct. However!
"When the response arrives" happens to be an unpredictable event in the future. It might be after 10 milliseconds, it might take 2 seconds, or the request might time out altogether. Even 10 milliseconds is already an eternity, compared to the time it takes your browser to execute all other code in your script. You can be quite sure that by the time $.ajax returns, the success callback has not run yet.
When you pass a callback (success) to a function ($.ajax) and the callback is not run before the function returns, this is called an asynchronous callback, "async" for short. When a callback might be invoked async, it is important for the function to guarantee that it always runs async, because this type of situation needs to be handled in an entirely different way from when the callback is invoked synchronously (i.e., before the function returns). You can read more about the technicalities in this blogpost. So this is exactly what $.ajax guarantees: it will never invoke the success (or error) callback before it returns, even in the hypothetical situation that the response would arrive fast enough.
Right after $.ajax returns, your Load function returns, at which point your _getChartDisplayDiv function continues to execute. Almost immediately after that, you intend to read _this.spotName. $.ajax has already returned, so you might hope that at this point, the success callback has already been invoked.
Unfortunately for you, async callbacks are more stubborn than that. Not only does an async callback not run until the function to which you pass it returns; it does not run until any currently executing function returns. Besides $.ajax, Load needs to return, _getChartDisplayDiv needs to return, any function that was calling _getChartDisplayDiv needs to return, and so forth. The entire call stack needs to unwind. Only then (and when the response actually arrives, which is likely to be many milliseconds later) will the success callback be invoked. This game rule is called the event loop in JavaScript.
The solution is simpler than you might expect: you just need to invert the order of control. Rather than trying to force the data out of a request when you want to update the chart, you can update the chart when the response arrives, and rather than trying to update the chart directly, you can just trigger the request. Specifically in your case, you just need to make three changes:
In the places where you currently call _getChartDisplayDiv, call _this.Load instead.
Remove the line that calls _this.Load inside the _getChartDisplayDiv function.
At the end of the success handler, add a line that calls _getChartDisplayDiv.
Incidentally, using a proper application framework will make it much easier to manage this kind of thing. In your case, I recommend trying Backbone; it builds on top of Underscore and jQuery and it is unopinionated, so you can gradually adopt it without having to radically change the way you work.
I am not familiar with underscore.js. For jQuery you have two options, which you can use as an inspiration for your case. Untested code:
1. Callback function
You provide a callback function:
$('.mydiv').myPlugin({ // Pass options Object to plugin
venuId: '123',
getType: function(type) {
console.log(type); // Example accessing internal data
}
});
Your plugin code:
(function( $ ) {
$.fn.myPlugin = function(opt) {
this.filter('div').each(function() {
const settings = $.extend({
namespace: 'myPlugin',
type: 'local'
getType: function() {},
// otherSettings: 'as needed',
}, opt);
// plugin code here...
if(typeof settings.getType === 'function') {
settings.getType(settings.type);
}
});
return this;
};
}( jQuery ));
2. Plugin method
You define plugin method(s) that can be called:
$('#mydiv').myPlugin({ // Pass options Object to plugin
venuId: '123'
});
console.log($('#mydiv').myPlaugin('getType'));
Your plugin code:
(function( $ ) {
$.fn.myPlugin = function(opt) {
this.filter('div').each(function() {
const settings = $.extend({
namespace: 'myPlugin',
type: 'local',
// otherSettings: 'as needed',
}, opt);
this.getType = function() {
return settings.type;
}
let firstArg = arguments[0];
if(typeof firstArg === 'string') {
let func = this[firstArg];
if(typeof func === 'function') {
var args = [];
for(var i = 1; i < arguments.length; i++) {
args.push(arguments[i]);
}
return func.apply(this, args);
}
} else {
// plugin init code here...
}
});
return this;
};
}( jQuery ));
I have a simple code that involves asynchronous tasks:
// The NewsFeed Class
function NewsFeed() {
this.loadFeed = function() {
$.ajax({
url: "http://www.example.com",
success: function() {
// doSomething here, and call onload.
}
});
}
// Need to implement onload here somehow
this.onload = ?;
this.loadFeed();
return this;
}
NewsFeed.constructor = NewsFeed;
// In main JS file
var newsFeed = new NewsFeed();
$(function() {
// do something
newsFeed.onload = function() { // do something when news feed is loaded };
}
My requirement is that, onload of NewsFeed needed to be executed in both case:
If the loadFeed's ajax is finished, run it immediately.
If the loadFeed's ajax is not done yet, run after it.
There's really no need to use new or constructor when you don't need new instances, all you really need is to run a simple ajax function that gets the result from cache if it hasn't changed.
function newsFeed() {
return $.ajax({
url : "http://www.example.com",
cache : true // let the browser handle caching for you
});
}
// In main JS file
$(function() {
newsFeed().then(function() {
// do something when news feed is loaded
});
});
The new pattern instead of callback is using Promises
see:
https://github.com/kriskowal/q
With jquery you can use:
https://api.jquery.com/category/deferred-object/
now the code:
function NewsFeed() {
function loadFeed() {
var deferred = $.Deferred();
$.ajax({
url: "http://www.example.com",
success: function(data) {
deferred.resolve(data);
},
error: function(data) {
deferred.reject(data);
}
});
return deferred.promise();
}
this.loadFeed = loadFeed;
return this;
}
NewsFeed.constructor = NewsFeed;
// In main JS file
var newsFeed = new NewsFeed();
newsFeed.loadFeed().done(function(data){
//data loaded successfully
})
.fail(function(data){
//ajax request failed
})
.always(function(){
//finally:
});
function moveIt(result, finish) {
$result = $(result);
$result.find('#main-content-wrapper').appendTo('#aem-content');
$result.appendTo('#scriptDiv');
if (finish !== undefined) {
finish();
}
}
function isAuthSpace(path) {
if (path.toLowerCase().indexOf("shop/") > 0) return true;
return false;
}
function finishInjecting() {
ProcessInjection("div.dyna-prd-lnk", parseDivTag, pumpDivTag, "Shop.aspx/GetLinks");
}
function AEMLoadError(isAuth) {
var fileToLoad = "unAuth.html";
if (isAuth) {
fileToLoad = "auth.html";
}
$("#aem-content").load(fileToLoad, finishInjecting);
}
function breakAEMLoadPath(path) {
return BreakTheAEMLoadPath === true ? "2" : path;
}
function PullAEM(path, finish) {
var isAuth = isAuthSpace(path);
var ppath = breakAEMLoadPath(path);
$.ajax({
url: ppath,
success: function (result) {
moveIt(result, finish);
},
error: function () {
AEMLoadError(isAuth);
},
dataType: "html"
});
}
When I call the above function PullAEM(path, finish), no matter what value I put in path parameter, the ajax call calls the success function, if the path has garbage in it, say it's empty, the call succeeds (even though it should fail). When it should fail, the result contains the contents of the current page which is not what path is pointing to. Anyone have any idea what I'm doing wrong?
Thanks for everyone answering so fast. I'm not sure what the problem was but after I cleaned it all up to post it up here it worked great! Though, it ay have been something you both were saying.
This is working perfectly....
Is there anyway to determine when an external script has loaded AND executed? I know that we can determine when it has been loaded using the onloadevent like this:
<script src=script.js async></script>
<script>
document.getElementsByTagName('script')[0].onload = function(){...}
</script>
But what about loaded and executed?
Here is a method to load multiple JS scripts using jQuery deferreds and $.ajax method. Message on console will be printed when BOTH JS files are loaded & executed
Demo http://jsbin.com/qumojobawe/2/edit?html,js,output
var deferreds = [];
var jsFiles = ['https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-debug.js', 'https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.9.0/moment.js'];
$.each(jsFiles, function(idx, url) {
deferreds.push(jQuery.ajax({
type: "GET",
url: url,
dataType: "script",
cache: true
}));
});
deferreds.push($.Deferred(function(deferred) { $(deferred.resolve); }));
$.when.apply(this, deferreds).done(function() {
console.log("KnockoutJS & MomentJs is loaded", ko, moment);
});
If script loads additional components and does not initialize immediately you can use following wait() method which will wait until certain condition is met by rechecking it on specified interval
var wait = function (condFunc, readyFunc, checkInterval) {
var checkFunc = function () {
if (condFunc()) {
readyFunc();
}
else {
setTimeout(checkFunc, checkInterval);
}
};
checkFunc();
};
For example, following code will check when current time number of seconds ends with zero every 10 milliseconds and executes function when condition is true:
wait(
function() { return new Date().getSeconds() % 10 == 0 },
function() { console.log("this will be called when time is 0, 10, 20, 30, etc seconds", new Date()); },
10);
Demo http://jsbin.com/fayenigixo/1/edit
If you are asking about script, that you can modify, then you can write a callback function in external script. You can read more about it here: http://www.w3schools.com/jquery/jquery_callback.asp
If you are asking about external script, that you can not modify, then you should read API documentation, if it exists. For example, here you can find a YouTube's API docs: https://developers.google.com/youtube/js_api_reference#Functions
You can check if a namespace is "loaded" with a method like this :
var isNamespaceDefined = function(moduleName) {
var fields = moduleName.split('.'), cur = window;
for(var i=0; i<fields.length; i++){
if(typeof cur[fields[i]] === "undefined") return false;
cur = cur[fields[i]];
}
return true;
};
usage : isNamespaceDefined("my.module.function")
Combined with a setTimeout to check the loading:
var doWhenReady = function(){
if(isNamespaceDefined("my.function")){
// redefining the function;
var _myFunction = my.function;
my.function = function(){
// do things Before the call
_myFunction.apply(null, arguments);
// do things After the call
};
}
else{
setTimeout(doWhenReady , 100);
}
}
A simple solution, but may be added with some time check and error callback
I have 3 ajax call in one function and checkAjaxCompletion which checks each ajax completion flag.
What the code below does is send multiple separate ajax calls and interval method checks completion flags to determine whether to proceed or keep interval. (I know clearInterval is not shown but the point is I want to use something other than interval)
Current code is:
function manyAjax() {
setInterval( function() { checkAjaxCompletion(); } , 200);
ajax1();
ajax2();
ajax3();
}
function ajax1() {
//send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}
function ajax2() {
//send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}
function ajax3() {
//send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}
function checkAjaxCompletion() {
if(ajax1_flag == 1 && ajax2_flag == 1 && ajax3_flag == 1) {
//everything went success, do some process
}
else if(ajax1_flag == 2 || ajax2_flag == 2 || ajax3_flag == 2) {
//some ajax failed, do some process
}
else {
//all ajax have not been completed so keep interval i.e. do nothing here
}
}
But I'm hesitating to depend on using interval function because calling it so often seem such waste of memory. There must be better way to do. I'm thinking if observer pattern can be applied here but would like to hear opinions.
It is observer-notifier, if you want to call it that - but each of your ajax calls will more than likely have a callback in javascript when they complete. Why not call checkAjaxCompletion() at the end of each of them, and do nothing if you're still waiting on others?
Dustin Diaz does a great job with this example.
function Observer() {
this.fns = [];
}
Observer.prototype = {
subscribe : function(fn) {
this.fns.push(fn);
},
unsubscribe : function(fn) {
this.fns = this.fns.filter(
function(el) {
if ( el !== fn ) {
return el;
}
}
);
},
fire : function(o, thisObj) {
var scope = thisObj || window;
this.fns.forEach(
function(el) {
el.call(scope, o);
}
);
}
};
The publisher:
var o = new Observer;
o.fire('here is my data');
The subscriber:
var fn = function() {
// my callback stuff
};
o.subscribe(fn);
To unsubscribe:
var fn = function() {
// my callback stuff
};
o.subscribe(fn);
// ajax callback
this.ajaxCallback = function(){
$.ajax({
type: "POST",
url: ajax.url,
data: {key: value},
async : !isAll,// false使用同步方式执行AJAX，true使用异步方式执行ajax
dataType: "json",
success: function(data){
if(data.status == 'successful'){
selfVal.parent().find('.msg').addClass('ok').html(msg.ok);
}else if(data.status == 'failed'){
checkRet = false;
selfVal.parent().find('.msg').removeClass('ok').html(msg.error);
}else{
checkRet = false;
}
return this;
}
});
}
return this;
Maybe you want to check your inputvalue callback ajax in your form;
You can view my website Demo, hope help you.
http://6yang.net/myjavascriptlib/regForm
Okay my idea was to make your own object that can handle sending an array of requests, keep a history of each request and do what i'm gonna call 'postProccessing' on each response, here is a probably very dodgy bit of code to hopefully demonstrate what I am thinking.
var Ajax = function() {
var request, callback, lst;
if (window.XMLHttpRequest) {
request = new XMLHttpRequest();
} else if (window.ActiveXObject) {
request = new ActiveXObject("Microsoft.XMLHTTP");
}
request.onreadystatechange = handleResponse;
this.history = [{}];
this.send = function(args) {
for (var i = 0; i < args.length; i++) {
if (args.url) {
request.open(args.type || 'GET', args.url);
}
request.send(args.data || null);
callback = args.callback;
lst++;
}
}
function handleResponse() {
var response = {
url: '',
success: true,
data: 'blah'
};
history.push(response);
if (postProccess()) {
callback();
}
}
function postProcess() {
if (this.history[lst].success) {
return true;
} else {
return false;
}
}
}