I have a javascript function that creates a leaflet layer group, adds it to a map, removes it and then repeats. Each time, it goes through a json array that has the data which is placed in the layer group. The effect is an animation of data points on the map.
There are two data sets which are formatted to be animated with this function. Let's call them Nowcast and Forecast. In my app, if I run the animations in the following sequence:
Nowcast, Forecast, Nowcast, Forecast, Nowcast
On the third Nowcast run, it looks like some of the data from the Forecast shows up along with the Nowcast data. Not all the data, and only for a few iterations, but then it just sits there and does not disappear when the animation is over. The only way to get this weird residual data is to run the Forecast animation again. (running the Nowcast again does not remove it).
Anyway, here is the function:
function animateAshData(inputData,dataLayer) {
var currentTime = inputData.ashData[t];
var currentAshData = currentTime.concentrations;
window.Android.toLogCat("t = " + currentTime.date + " " + t);
window.Android.toLogCat("Current set size= " + currentAshData.length);
if (dataLayer != undefined) { //The map has a data layer already been created from previous time step, so remove it
removeDataLayer(dataLayer);
}
var currentAshLayerGroup = new L.LayerGroup();
for (j = 0; j<currentAshData.length; j++) {
L.marker([currentAshData[j].lat, currentAshData[j].lon],{icon: ashIcon}).addTo(currentAshLayerGroup);
map.addLayer(currentAshLayerGroup);
};
t = t+1;
// Queue up the animation to the next time step
tid = setTimeout(function(){
if (t > finalt) {
//end of animation
window.Android.toLogCat("Done with animation");
removeDataLayer(currentAshLayerGroup);
window.clearTimeout(tid);
} else {
// delete currentTime.concentrations;
clearMap();
animateAshData(inputData,currentAshLayerGroup);
}
}, 100);
My first thought was that the layer groups were somehow persisting, even though I had a map.removeLayer(layer) in there (although it is mysterious why it takes 3 iterations instead of just 2 for this to show up...). So, I made a removeDataLayer() function and added a layer.clearLayers(). This did not work either. I finally added the function from here Clear all polylines from leaflet map to just try clearing everything, but this still did not work. Here is my removeDataLayer function:
function removeDataLayer(layer){
map.removeLayer(layer);
layer.clearLayers();
clearMap();
};
function clearMap(){
for(i in map._layers){
if(map._layers[i]._path != undefined)
{
try{
map.removeLayer(map._layers[i]);
}
catch(e){
console.log("problem with " + e + map._layers[i]);
}
}
}
};
Anyway, I can't imagine I am the only one with problems with leaflet layers interfering with each other and/or problems removing them completely. Thanks in advance.
I am trying to implement the new structure of here map(asp.net web app) , however, I cannot see the features of passing the location information and retrieving the certain address via javascript and stick that info with a bubble on the marker.
Appreciate for any advises.
cheers
I think you are looking to make multiple concurrent reverse geocode requests. There is no problem in doing this, since the calls are asynchronous, you just need to keep a count on which requests have completed, and call your "do-after-all-completed" stuff once at the end:
e.g:
function concurrentSearch(map){
// we will put our address markers into this container
addressContainer = new nokia.maps.map.Container();
managersFinished = 0;
//Locations to be displayed
latLngs= [[10,30], [-117.5, 15.3] ... etc];
var i = latLngs.length;
while(i--) {
nokia.places.search.manager.reverseGeocode({
latitude: latLngs[i][0],
longitude: latLngs[i][1],
onComplete: processResults
});
}
}
With a callback function as shown:
function processResults(data, requestStatus) {
if (requestStatus == "OK") {
// if we are finished, we add a marker for the mapped position
var marker = new nokia.maps.map.StandardMarker(data.location[0].position);
marker.content = data.location[0].address.text; // add your content here
addressContainer.objects.add(
marker);
//increment the counter to notify another manager has finished
managersFinished++;
} else if(requestStatus === "ERROR") {
// we'll also increment in case of an error
managersFinished++;
}
// if all managers are finished, we call the final function
if(managersFinished === latLngs.length) {
onAllManagersFinished();
}
}
And the final clean up:
function onAllManagersFinished() {
//we get the bounding box of the container
var bbox = addressContainer.getBoundingBox();
// if the bounding box is null then there are no objects inside
// meaning no markers have been added to it
if (bbox != null) {
// we have at least one address mapped
// so we add the container and zoomTo it
map.objects.add(addressContainer);
map.zoomTo(bbox);
} else {
// otherwise we'll pop up an error message
alert("There are no addresses to show :(");
}
}
Futhermore, you could add a single event handler on the container, which could open the infobubbles for all of your locations:
addressContainer.addListener(
"click",
function (evt) {
infoBubbles.openBubble(evt.target.content, // content is your own stuff...
evt.target.coordinate);
}
);
If you need to pass in more of your information when reverse-geocoding, you can do it in the manner described in the question here
The solution to a similar problem (multiple geocoding requests) can be found here.
NOT A DUPLICATE AS I HAVE YET TO FOUND A SATISFYING ANSWER ON OTHER THREADS:
Load and execute javascript code SYNCHRONOUSLY
Loading HTML and Script order execution
Load and execute javascript code SYNCHRONOUSLY
Looking for native Javascript answers, no jQuery, no requireJS, and so forth please :)
SUMMARY OF THE ENTIRE QUESTION:
I want to asynchronously load scripts but have ordered execution
I am trying to enforce that the code in the inserted script elements execute exactly in the same order as they were added to the dom tree.
That is, if I insert two script tags, first and second, any code in first must fire before the second, no matter who finishes loading first.
I have tried with the async attribute and defer attribute when inserting into the head but doesn't seem to obey.
I have tried with element.setAttribute("defer", "") and element.setAttribute("async", false) and other combinations.
The issue I am experiencing currently has to do when including an external script, but that is also the only test I have performed where there is latency.
The second script, which is a local one is always fired before the first one, even though it is inserted afterwards in the dom tree ( head ).
A) Note that I am still trying to insert both script elements into the DOM. Ofcourse the above could be achieved by inserting first, let it finish and insert the second one, but I was hoping there would be another way because this might be slow.
My understanding is that RequireJS seems to be doing just this, so it should be possible. However, requireJS might be pulling it off by doing it as described in A).
Code if you would like to try directly in firebug, just copy and paste:
function loadScript(path, callback, errorCallback, options) {
var element = document.createElement('script');
element.setAttribute("type", 'text/javascript');
element.setAttribute("src", path);
return loadElement(element, callback, errorCallback, options);
}
function loadElement(element, callback, errorCallback, options) {
element.setAttribute("defer", "");
// element.setAttribute("async", "false");
element.loaded = false;
if (element.readyState){ // IE
element.onreadystatechange = function(){
if (element.readyState == "loaded" || element.readyState == "complete"){
element.onreadystatechange = null;
loadElementOnLoad(element, callback);
}
};
} else { // Others
element.onload = function() {
loadElementOnLoad(element, callback);
};
}
element.onerror = function() {
errorCallback && errorCallback(element);
};
(document.head || document.getElementsByTagName('head')[0] || document.body).appendChild(element);
return element;
}
function loadElementOnLoad(element, callback) {
if (element.loaded != true) {
element.loaded = true;
if ( callback ) callback(element);
}
}
loadScript("http://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.min.js",function() {
alert(1);
})
loadScript("http://ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js",function() {
alert(2);
})
If you try the above code in like firebug, most often it will fire 2, and then 1. I want to ensure 1 and then 2 but include both in the head.
if I insert two script tags, first and second, any code in first must fire before the second, no matter who finishes loading first. I have tried with the async attribute and defer attribute
No, async and defer won't help you here. Whenever you dynamically insert script elements into the DOM, they are loaded and executed asynchronically. You can't do anything against that.
My understanding is that RequireJS seems to be doing just this
No. Even with RequireJS the scripts are executed asynchronous and not in order. Only the module initialiser functions in those scripts are just define()d, not executed. Requirejs then does look when their dependencies are met and executes them later when the other modules are loaded.
Of course you can reinvent the wheel, but you will have to go with a requirejs-like structure.
Ok, I think I have now came up with a solution.
The trick is that we keep track of each script to be loaded and their order as we insert them into the dom tree. Each of their callback is then registered accordingly to their element.
Then we keep track of when all has finished loading and when they all have, we go through the stack and fire their callbacks.
var stack = [];
stack.loaded = 0;
function loadScriptNew(path, callback) {
var o = { callback: callback };
stack.push(o);
loadScript(path, function() {
o.callbackArgs = arguments;
stack.loaded++;
executeWhenReady();
});
}
function executeWhenReady() {
if ( stack.length == stack.loaded ) {
while(stack.length) {
var o = stack.pop();
o.callback.apply(undefined, o.callbackArgs);
}
stack.loaded = 0;
}
}
// The above is what has been added to the code in the question.
function loadScript(path, callback) {
var element = document.createElement('script');
element.setAttribute("type", 'text/javascript');
element.setAttribute("src", path);
return loadElement(element, callback);
}
function loadElement(element, callback) {
element.setAttribute("defer", "");
// element.setAttribute("async", "false");
element.loaded = false;
if (element.readyState){ // IE
element.onreadystatechange = function(){
if (element.readyState == "loaded" || element.readyState == "complete"){
element.onreadystatechange = null;
loadElementOnLoad(element, callback);
}
};
} else { // Others
element.onload = function() {
loadElementOnLoad(element, callback);
};
}
(document.head || document.getElementsByTagName('head')[0] || document.body).appendChild(element);
return element;
}
function loadElementOnLoad(element, callback) {
if (element.loaded != true) {
element.loaded = true;
if ( callback ) callback(element);
}
}
loadScriptNew("http://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.js",function() {
alert(1);
});
loadScriptNew("http://ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js",function() {
alert(2);
});
Ok, some of you might argue that there is missing info in the question, which I will give you and here we are actually just solving the callback. You are right. The code in the script is still executed in the wrong order, but the callback is now.
But for me this is good enough, as I intend to wrap all code that is loaded in a method call, alá AMD, such as a require or define call and will put on stack there, and then fire them in the callback instead.
I am still hoping out for Asad and his iframe solution, which I believe might provide the best answer to this question. For me though, this solution will solve my problems :)
I am posting here just like a draft
This do not work because cross-domain police
Here the idea is to obtain all scripts first and when they are in memory, execute them in order.
function loadScript(order, path) {
var xhr = new XMLHttpRequest();
xhr.open("GET",path,true);
xhr.send();
xhr.onreadystatechange = function(){
if(xhr.readyState == 4){
if(xhr.status >= 200 && xhr.status < 300 || xhr == 304){
loadedScripts[order] = xhr.responseText;
}
else {
//deal with error
loadedScripts[order] = 'alert("this is a failure to load script '+order+'");';
// or loadedScripts[order] = ''; // this smoothly fails
}
alert(order+' - '+xhr.status+' > '+xhr.responseText); // this is to show the completion order. Careful, FF stacks aletrs so you see in reverse.
// am I the last one ???
executeAllScripts();
}
};
}
function executeAllScripts(){
if(loadedScripts.length!=scriptsToLoad.length) return;
for(var a=0; a<loadedScripts.length; a++) eval(loadedScripts[a]);
scriptsToLoad = [];
}
var loadedScripts = [];
var scriptsToLoad = [
"http://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.min.js",
"http://ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js",
"http://nowhere.existing.real_script.com.ar/return404.js"
];
// load all even in reverse order ... or randomly
for(var a=0; a<scriptsToLoad.length; a++) loadScript(a, scriptsToLoad[a]);
After a while of fiddling around with it, here is what I came up with. Requests for the scripts are sent off immediately, but they are executed only in a specified order.
The algorithm:
The algorithm is to maintain a tree (I didn't have time to implement this: right now it is just the degenerate case of a list) of scripts that need to be executed. Requests for all of these are dispatched nearly simultaneously. Every time a script is loaded, two things happen: 1) the script is added to a flat list of loaded scripts, and 2) going down from the root node, as many scripts in each branch that are loaded but have not been executed are executed.
The cool thing about this is that not all scripts need to be loaded in order for execution to begin.
The implementation:
For demonstration purposes, I am iterating backward over the scriptsToExecute array, so that the request for CFInstall is sent off before the request for angularJS. This does not necessarily mean CFInstall will load before angularJS, but there is a better chance of it happening. Regardless of this, angularJS will always be evaluated before CFInstall.
Note that I've used jQuery to make my life easier as far as creating the iframe element and assigning the load handler is concerned, but you can write this without jQuery:
// The array of scripts to load and execute
var scriptsToExecute = [
"http://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.min.js?t=" + Date.now(),
"http://ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js?t=" + Date.now()
];
// Loaded scripts are stored here
var loadedScripts = {};
// For demonstration purposes, the requests are sent in reverse order.
// They will still be executed in the order specified in the array.
(function start() {
for (var i = scriptsToExecute.length - 1; i >= 0; i--) {
(function () {
var addr = scriptsToExecute[i];
requestData(addr, function () {
console.log("loaded " + addr);
});
})();
}
})();
// This function executes as many scripts as it currently can, by
// inserting script tags with the corresponding src attribute. The
// scripts aren't reloaded, since they are in the cache. You could
// alternatively eval `script.code`
function executeScript(script) {
loadedScripts[script.URL] = script.code
while (loadedScripts.hasOwnProperty(scriptsToExecute[0])) {
var scriptToRun = scriptsToExecute.shift()
var element = document.createElement('script');
element.setAttribute("type", 'text/javascript');
element.setAttribute("src", scriptToRun);
$('head').append(element);
console.log("executed " + scriptToRun);
}
}
// This function fires off a request for a script
function requestData(path, loadCallback) {
var iframe = $("<iframe/>").load(function () {
loadCallback();
executeScript({
URL: $(this).attr("src"),
code: $(this).html()
});
}).attr({"src" : path, "display" : "none"}).appendTo($('body'));
}
You can see a demo here. Observe the console.
cant you nest the loading using ur callbacks?
ie:
loadScript("http://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.min.js",function() {
alert(1);
loadScript("http://ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js",function() {
alert(2);
})
})
Here's my code:
if(typeof(Storage)!==undefined) {
// Web storage support
if(localStorage.hashes != "") {
var hashes = jQuery.parseJSON(localStorage.hashes);
for (var i = 0; i < hashes.length; i++) {
// Do stuff here
}
}
else {
var hashes = [];
}
}
else {
// No web storage support
}
I don't really know what's going on, but when I try to load the page with this code from a device for the first time, the rest of my code doesn't work the way it should. However, if I comment it out then visit the page for the first time everything works. I can then uncomment it, reload the page, and everything will continue to work. This is really the best I can describe what's happening.
I believe you could have done a little more debugging before posting this.
Have you tried logging/ adding checks (to see where exactly this issue is coming from and what the error is) ?
But since we're here, here are my tips for localStorage :
Use modernizr (http://modernizr.com/)
if(Modernizr.localstorage){ /* Your code */}
Make some generic get and set functions
function get(key) {
if(Modernizr.localstorage) {
if(localStorage[key] != null) {
return localStorage[key];
}
}
return null;
}
function set(key, value) {
if(Modernizr.localstorage) {
localStorage[key] = value;
}
return null;
}
This is pretty rough, you tweek it to make it safer and respond to your needs
Put try/catch inside your get and set functions, you don't want write operations to impact your program
I figured it out! So in the above code I check if they had localStorage available, and if they do, I just assume that they have some hashes stored in there. This obviously creates a problem on their first visit as they wouldn't have any hashes saved yet. So I have to check if they have any, if they do, then do the for loop, otherwise just set it to an empty array. Like so!
if(typeof(Storage) !== "undefined") {
// Web storage support
if(localStorage.hashes != "") {
hashes = JSON.parse(localStorage.getItem("hashes"));
if(hashes) {
for (var i = 0; i < hashes.length; i++) {
// Do Stuff
}
} else {
hashes = [];
}
}
else {
hashes = [];
}
}
else {
// No web storage support
hashes = [];
}
Thanks to jbabey for tips on cleaning up my code some!
I grabbed a bit of code to do some paging with jQuery, via Luca Matteis here
Paging Through Records Using jQuery
I've made some edits to the paging script so that I can use the same code to provide paging of different content in different locations on the same site.
For the most part, I think it works, except that I get a jsonObj is undefined error in firebug.
When I use alert(jsonObj.toSource()), I am shown the variables that I am trying to populate, but at the same time, the script dies because of the error.
I can't figure out why I am getting this conflict of 'undefined' and yet I can easily out put the 'undefined' values in an alert. I can even say alert(jsonObj.name), and it will give me that value, but still launch an jsonObj is undefined error.
Here's the code I'm using
var pagedContent = {
data: null
,holder: null
,currentIndex : 0
,init: function(data, holder) {
this.data = data;
this.holder=holder;
this.show(0); // show last
}
,show: function(index) {
var jsonObj = this.data[index];
if(!jsonObj) {
return;
}
var holdSubset='';
for(i=0;i<=4; i++){
jsonObj=this.data[index+i];
this.currentIndex = index;
if(this.holder=='div#firstList'){
var returnedId = jsonObj.id;
var returnedName = jsonObj.name;
var calcScore=this.data[index+i].score/this.data[0].score*100;
var resultInput="<div ' id='"+returnedId+"'><div class='name'>"+returnedName+"</div><div class='score'><div style='width:"+calcScore+"%;'></div></div>";
}
if(this.holder=='div#secondList'){
var name=jsonObj.name;
var city=jsonObj.city;
var region=jsonObj.state;
var resultInput='<li><div>'+name+'</div<div>'+city+'</div><div>'+region+'</div></li>';
}
holdSubset= holdSubset+resultInput;
}
jQuery(this.holder).html('<br/>'+holdSubset);
if(index!=0){
var previous = jQuery("<a>").attr("href","#").click(this.previousHandler).text("< previous");
jQuery(this.holder).append(previous);
}
if(index+i<this.data.length){
var next = jQuery("<a style='float:right;'>").attr("href","#").click(this.nextHandler).text("next >");
jQuery(this.holder).append(next);
}
}
,nextHandler: function() {
pagedContent.show(pagedContent.currentIndex + 5);
return false;
}
,previousHandler: function() {
pagedContent.show(pagedContent.currentIndex - 5);
return false
}
};
I call the function like this
pagedContent.init(json.users.locations, 'div#secondList');
The json looks like this
{"locations" : [ {"id":"21319","name":"Naugatuck American Legion","city":"Ansonia","region":"Connecticut"},{"id":"26614","name":"Studio B789","city":"Acton","region":"Maine"},{"id":"26674","name":"Deering Grange Hall","city":"Bailey Island","region":"Maine"},{"id":"27554","name":"Accu Billiards","city":"Acushnet","region":"Massachusetts"}]}
I may have found the problem with your code:
for(i=0;i<=4; i++){
jsonObj=this.data[index+i];
(...)
When you call show(0) you set index to 0. You expect a fixed number of items in the array (5 in the range [0..4]) but there are only 4 locations in your data.
If you are using console.log to trace the problems in firebug you might find that it is a problem with firebug. Try just running console.log on it's own.
If it is a problem with firebug try updating it. There are some development versions around which might fix the problem.
I had a similar problem and fixed it by doing the above.