I have a little problem with a homemade script, first I'll give you the script
var heighti = $(window).height();
var imageLoading = new Array();
$('.fullHeight').css({'height' : heighti});
var now,hour,minute,second,dateNow = new Array(),countImg=0,i=0,countDateNow = 0;countImg=0,countThis=0,countDateNowAj=0;
/* GET THIS HOUR */
now = new Date();
hour = now.getHours();
minute = now.getMinutes();
second = now.getSeconds();
function date(){
//Function to get date
}
function loadImage(){
countThis = 0;
while(countThis < 6){
date();
var imgOn = 'uploads/original/'+dateNow[countDateNowAj]+'.jpg';
console.log(imgOn);
var img = $("<img />").attr('src', imgOn)
.load(function(){
imageLoading[i] = imgOn ;
i++;
})
.error(function(){
console.log('This is the image now : '+imgOn);
imageLoading[i] = 'images/noimage.jpg';
i++;
});
countThis++;
countDateNowAj++;
}
}
setInterval("dateImg()",1000);
setTimeout("loadImage()",0);
setInterval("loadImage()",5000);
So this is my function, everything works but when I want to do imageLoading[i] = imgOn; the script take always the last value.
This is a log of what I'm talking about : http://minus.com/mpWvBsXkQ
First I check the time
After I check the image who is gonna be checked
And at the end I check the name of imageLoading[i] = imgOn;
And I always get the last time and not every second.
I hope you'll understand my query.
In the load and error handler functions, you are using variables from the outer scope (in this case the scope will be the loadImage function) asynchronously, but they will be changed synchronously as part of the loop. If you want to have them held constant until the handlers are actually called, you will need to use a closure:
function loadImage(){
function imageLoader(i, imgOn) {
console.log(imgOn);
var img = $("<img />").attr('src', imgOn)
.load(function(){
imageLoading[i] = imgOn ;
})
.error(function(){
console.log('This is the image now : '+imgOn);
imageLoading[i] = 'images/noimage.jpg';
});
}
for(countThis = 0; countThis < 6; countThis++, countDateNowAj++) {
date();
imageLoader(i++, 'uploads/original/'+dateNow[countDateNowAj]+'.jpg');
}
}
In this case, the imageLoader inner function becomes the scope that the load and error handlers run in, so the values of i and imgOn are as you would expect rather than always being the last values they had when the loop finished running.
Declare the imageLoading outside the loop like
var imageLoading = [];
Related
I have a problem calling the onload() function of a new image object when that image is immediately set as an object property. My parser tells me that imageMap[featureId].onload is not a function. I don't get why the imageMap[featureId] isn't synonymous with the image itself? The resourceList is used as an argument to preloadResource(). I have a setinterval elsewhere waiting for the loaded count to equal the resource count. Any ideas please?
var resourceList = ["path.png","path.png","path.png","path.png"];
var loadedResource = 0;
function preloadResource(resArr)
{
var buildIndex = 1;
for (i = 1; i <= resArr.length; i++)
{
var featureId = "feature" + buildIndex;
imageMap[featureId] = new Image();
imageMap[featureId].path = resArr[(i - 1)];
buildIndex++;
imageMap[featureId].onload(function () {loadedResource++;})
imageMap[featureId].src = resArr[(i -1)];
}
}
The error is telling you the problem: "onload is not a method."
imageMap[featureId].onload = function () {loadedResource++;};
or use addEventListener
I am facing a problem with setInterval being used in a loop.
I have a function subscribeFeed( ) which takes an array of urls as input.
It loops through the url array and subscribes each url to getFeedAutomatically() using a setInterval function.
so if three URL's are there in the array, then 3 setInterval's will be called.
The problem is
1)how to distinguish which setInterval is called for which URL.
2)it is causing Runtime exception in setInterval( i guess because of closure problem in javascript)
//constructor
function myfeed(){
this.feedArray = [];
}
myfeed.prototype.constructor= myfeed;
myfeed.prototype.subscribeFeed =function(feedUrl){
var i=0;
var url;
var count = 0;
var _this = this;
var feedInfo = {
url : [],
status : ""
};
var urlinfo = [];
feedUrl = (feedUrl instanceof Array) ? feedUrl : [feedUrl];
//notifyInterval = (notifyInterval instanceof Array) ? notifyInterval: [notifyInterval];
for (i = 0; i < feedUrl.length; i++) {
urlinfo[i] = {
url:'',
notifyInterval:5000,// Default Notify/Refresh interval for the feed
isenable:true, // true allows the feed to be fetched from the URL
timerID: null, //default ID is null
called : false,
position : 0,
getFeedAutomatically : function(url){
_this.getFeedUpdate(url);
},
};
urlinfo[i].url = feedUrl[i].URL;
//overide the default notify interval
if(feedUrl[i].NotifyInterval /*&& (feedUrl[i] !=undefined)*/){
urlinfo[i].notifyInterval = feedUrl[i].NotifyInterval;
}
// Trigger the Feed registered event with the info about URL and status
feedInfo.url[i] = feedUrl[i].URL;
//Set the interval to get the feed.
urlinfo[i].timerID = setInterval(function(){
urlinfo[i].getFeedAutomatically(urlinfo[i].url);
}, urlinfo[i].notifyInterval);
this.feedArray.push(urlinfo[i]);
}
}
// The getFeedUpate function will make an Ajax request and coninue
myfeed.prototype.getFeedUpdate = function( ){
}
I am posting the same on jsfiddle
http://jsfiddle.net/visibleinvisibly/S37Rj/
Thanking you in advance
After some prototyping i found a answer ,which has the answer,move the closure outside
function myclass(){
}
myclass.prototype.funone= function(){
var counter =0;
var timerID;
timerID = setInterval( function(){
alert(counter++);
},1000);
}
myclass.prototype.funtwo= function(){
var timerID2;
var counter2 =50;
timerID2 = setInterval( function(){
alert(counter2++);
},2000);
}
myclass.prototype.funthree = function( ){
var urlArray =["google.com","yahoo.com"];
var timeArray =[15000,6000];
var timerID ;
for(var i=0;i<2; i++){
var url = urlArray[i];
var timerinterval = timeArray[i];
timerID = this.register( url,timerinterval);
}
}
myclass.prototype.register = function(url,timerInterval){
var myUrl =url;
var myTimer = timerInterval;
var timerID = setInterval( function(){
alert(myUrl+"with"+ myTimer);
},myTimer);
}
var m = new myclass( );
m.funthree( );
http://jsfiddle.net/visibleinvisibly/Q4SBG/13/
The move the index binding from the setInterval and pass the url and time interval.
It works perfectly
You might want to have a look at this answer (under "The this variable" at the bottom) about what the this value means.
The error in your code may have something to do with using a counter in a loop and creating closures depending on the counter. The simplest way to create such closures is.
for(i=0;i<len;i++){
object.myCallback = (function(counter){
return function(){
doSomethingWith(counter);
}
}(i));
}
When creating closures on the fly like that you should be careful not dragging large or large amounts of variables into the closure scope. The link above and code below shows how to do this safely.
I've changed some of the code to make it simpler and not copy stuff that doesn't need to be copied, the setInterval is setTimeout so it only does it once but it's the same idea.
//constructor
function MyFeed(){
this.feedArray = [];
}
MyFeed.prototype.subscribeFeed =function(feedUrl){
var i=0,urlInfo=[];
feedUrl = (feedUrl instanceof Array) ? feedUrl : [feedUrl];
for (i = 0; i < feedUrl.length; i++) {
feedUrl[i].isEnable=true;
feedUrl[i].called=false;
feedUrl[i].position=0;//not sure what this is supposed to do
//Set the interval to get the feed.
feedUrl[i].timerID = setTimeout(this.closures//changed this to timeout
.getFeedUpdate(this)
,feedUrl[i].notifyInterval||100//changed default value
);
this.feedArray.push(feedUrl[i]);
}
};
// The getFeedUpate function will make an Ajax request and coninue
MyFeed.prototype.getFeedUpdate = function( index ){
console.log("in getFeedUpdate, this is now:",this);
console.log("my feed url object:",this.feedArray[index].url);
};
//limit closure scope, define closure creators here
MyFeed.prototype.closures={
//this.closures.getFeedUpdate(this)
// will return a closure that calls this.getFeedUpdate
// with correct parameters
getFeedUpdate:function(me){
var index = me.feedArray.length;
return function(){
me.getFeedUpdate(index);
};
}
};
//code to test adding single feed
var mf = new MyFeed();
mf.subscribeFeed({
url:"I am last",
notifyInterval:1000
});
//add another single feed
mf.subscribeFeed({
url:"first.com"
});
//and another
mf.subscribeFeed({
url:"second.com"
});
//and add some more feeds in an array of feeds
mf.subscribeFeed([
{
url:"third"
},
{
url:"fifth"
},
{
url:"no, I am last",
notifyInterval:1500
}
]);
Try FireFox with the FireBug plugin or Chrome and press F12 to see the console, when the log statements log something you can click on it to see the details of the logged item. Very helpful to log objects like this or simple values like index
I am loading a json file and parsing it into an array in Javascript. One of the elements is the path to an image. I am not ready to load the images yet but I need to get the image's height. I know how to do that with code like the following (found on other stackoverflow pages)
function getimageheight(img) {
var tmpImg = new Image();
tmpImg.onload = function() {
var ht = this.height;
return ht+0;
}
tmpImg.src = img;
}
If I try to call this function in a loop, it returns undefined because the onload for the images is running slower than the loop. My actual code is this:
var j = 0;
$.each(cat.placemarks, function(index, mark) {
markers[cat.name][j] = [];
markers[cat.name][j].name = mark.name;
markers[cat.name][j].title = mark.title;
markers[cat.name][j].markerURL = mark.markerURL;
markers[cat.name][j].imageURL = mark.imageURL;
markers[cat.name][j].imageHEIGHT = getimageheight(projpath+mark.imageURL);
j++;
});
If I call the function once, it works. But calling it in a loop does not. How can I fix this?
If you store reference to data object in Img object used to load it, you can set the value of its properties after the loading is done. Hope that makes sense... Your data will not be ready to use before loading is complete tho. Heres the code
var total=cat.placemarks.length;//if an array, otherwise use another each cycle to get object count
var loaded=0;
$each(cat.placemarks, function(index, mark) {
markers[cat.name][j] = [];
var tmpImg = new Image();
tmpImg.refToObjWithNameOfYourChoice=markers[cat.name][j];
tmpImg.onload = function() {
this.refToObjWithNameOfYourChoice.imageHEIGHT=this.heigh;
loaded++;
if(loaded==total){
//markers data is ready to use - add function callback herer or sumthin'
}
}
tmpImg.src=projpath+mark.imageURL;
markers[cat.name][j].name = mark.name;
markers[cat.name][j].title = mark.title;
markers[cat.name][j].markerURL = mark.markerURL;
markers[cat.name][j].imageURL = mark.imageURL;
j++;
});
markers[cat.name][j].imageHEIGHT is undefined because getImageHeight() isn't returning anything. And naturally, the image load will occur much more slowly than your each() loop, so it won't do you any good to have getImageHeight() return something. You'll have to set up your load() callback to determine which image has been loaded and update the height of the corresponding markers element.
function show_alert(){
var month = oMonthList.value;
var day = oDayField.value;
var gametype = oGameTypeList.value;
var gamenum = oGameNumberField.value;
var gamename = oGameNameField.value;
var modname = oModNameField.value;
var phase = oPhaseList.value;
var phasenum = oPhaseNumberField.value;
var pagenum = oNameNumberField.value;
var repname = oReplacementNameField.value;
var modlink = oModLinkField.value;
alert(phase);
}
Why does this not show the alert when the function is called, but removing all variables except the one in question (var phase) does? I'm guessing it's something to do with syntax, but I cannot pin down the issue.
Did you make sure that your javascript code doesn't throw any exception? If some object is undeclared or undefined, the code may be aborted early thus alert() is not not executed.
I have this countdown script wrapped as an object located in a separate file
Then when I want to setup a counter, the timeout function in the countdown class can not find the object again that I have setup within the document ready.
I sort of get that everything that is setup in the document ready is convined to that scope,
however it is possible to call functions within other document ready´s.
Does anyone has a solution on how I could setup multiple counters slash objects.
Or do those basic javascript classes have to become plugins
This is the class
function countdown(obj)
{
this.obj = obj;
this.Div = "clock";
this.BackColor = "white";
this.ForeColor = "black";
this.TargetDate = "12/31/2020 5:00 AM";
this.DisplayFormat = "%%D%% Days, %%H%% Hours, %%M%% Minutes, %%S%% Seconds.";
this.CountActive = true;
this.DisplayStr;
this.Calcage = cd_Calcage;
this.CountBack = cd_CountBack;
this.Setup = cd_Setup;
}
function cd_Calcage(secs, num1, num2)
{
s = ((Math.floor(secs/num1))%num2).toString();
if (s.length < 2) s = "0" + s;
return (s);
}
function cd_CountBack(secs)
{
this.DisplayStr = this.DisplayFormat.replace(/%%D%%/g, this.Calcage(secs,86400,100000));
this.DisplayStr = this.DisplayStr.replace(/%%H%%/g, this.Calcage(secs,3600,24));
this.DisplayStr = this.DisplayStr.replace(/%%M%%/g, this.Calcage(secs,60,60));
this.DisplayStr = this.DisplayStr.replace(/%%S%%/g, this.Calcage(secs,1,60));
//document.getElementById(this.Div).innerHTML = this.DisplayStr;
$('#'+this.Div).text(this.DisplayStr);
$('#tel').text(parseInt( $('#tel').text() )+1);
if (this.CountActive) setTimeout(this.obj +".CountBack(" + (secs-1) + ")", 990);
}
function cd_Setup()
{
var dthen = new Date(this.TargetDate);
var dnow = new Date();
ddiff = new Date(dthen-dnow);
gsecs = Math.floor(ddiff.valueOf()/1000);
this.CountBack(gsecs);
}
and setting it up
$(document).ready(function() {
var cd1 = new countdown('cd1');
cd1.Div = "clk";
cd1.TargetDate = "08/15/2010 8:00 PM";
cd1.DisplayFormat = "%%D%% days, %%H%% hours, %%M%% minutes, %%S%% seconds until event AAA happens";
cd1.Setup();
firebug says it errors out with the timeout function
thanks, Richard
cd1 is defined in the local scope. setTimeout will run the function passed as parameter 1 in the window [global] scope, and in your case, window.cd1 is undefined.
The solution for your problem would to make cd1 a global variable. [Remove the "var" in your declaration of cd1]
Off topic: I recommend you look into using anonymous functions, as they can make your code much more pretty/legible at times.