pause event while function runs - javascript

I am writing an infinite scroll function and having it run if the $(window).scrollTop() is almost as large as the documents height, and it works perfectly...
The issue is that it takes a couple seconds for the new posts to load, and in that time, if the page was scrolled, the function was called multiple times before the document got larger and therefore did not load the posts the way I intented.
Can I add a line to a function that will pause a specific event (in this case the scroll event) until the function has finished executing?
function f(){
//stop $(window).scroll
//execute code
//allow $(window).scroll
}
$(window).scroll(function(){
if(condition){
f();
}
});

John Resig did a post on this awhile ago
Here is the code he used
didScroll = false;
$(window).scroll(function() {
didScroll = true;
});
setInterval(function() {
if ( didScroll ) {
didScroll = false;
// Check your page position and then
// Load in more results
}
}, 250);

You can use $.off to unbind an event, but I would recommend to just use a variable to keep track if its been triggered or not.
This snippet will prevent f from being called until the scrolling has been set to false again.
$(window).scroll(function(){
if(this.scrolling == undefined)
this.scrolling = false;
if(this.scrolling == false){
this.scrolling = true;
f();
}
});
function f(){
//execute code
window.scrolling = false;
}

You can remove the scroll event once it's called, then reattach it if/when the load posts request is completed:
function loadPosts() {
if (condition) { // e.g. scrollTop almost equal to document height.
$(window).off('scroll', loadPosts);
$('[selector]').load('[URL-to-posts]', function(posts) {
bindScroll();
// Display posts.
});
}
}
// Binds the scroll event.
function bindScroll() {
$(window).on('scroll', loadPosts);
}
$(bindScroll); // Call on document ready.

Related

How to start javascript setinterval once cleared?

I have a setinterval that runes every 5 seconds. this works fine on page load.
I have the following scenarios:
Load page with interval (WORKS)
press button and load new content and stopp interval(WORKS)
Once the new content is no longer desiered, dissmiss it, return to first content and start interval again(DOES NOT WORK)
I have saftys suchs as events for window.blur that also stops the interval so that the browser does not commponsate for all the missing intervals if i would change tabs or something. Keep in mind that step 3 did not work BUT if i would after step 3 change a tab and then return to my original page(execute blur) the interval would start working again.
NOTE all content loading here exept page load is done with ajax calls.
My code:
initializing:
$.automation.worker.bindIntervalEvent("#TanksContent", "/Tank/GetTanks", function() {
$.automation.tanks.tableInit();
});
binding function:
bindIntervalEvent: function (target, url, callback) {
$(window)
.on("focus.mine",
function() {
$.automation.worker.setUpdateInterval(target, url, callback);
})
.on("blur",
function() {
$.automation.worker.stopUpdateInterval();
}).trigger("focus.mine");
}
interval function:
setUpdateInterval: function (target, url, callback) {
if ($.automation.globals.globalInterval.value.length === 0) {
$.automation.globals.globalInterval.value.push(window.setInterval(
function () {
var options = {
loadTarget: target
}
$.automation.worker.getView(url,
function() {
if (callback)
callback();
},
options);
},
5000));
}
}
the function that stops the interval:
stopUpdateInterval: function () {
if ($.automation.globals.globalInterval.value.length === 0)
return;
console.log("deleting");
for (var i = 0; i <= $.automation.globals.globalInterval.value.length; i++) {
window.clearInterval($.automation.globals.globalInterval.value[i])
$.automation.globals.globalInterval.value.splice(i, 1);
console.log($.automation.globals.globalInterval.value.length);
}
}
when stopping the interval i also remove the window bindings:
unBindIntervalEvent: function() {
$(window).off("focus.mine");
$(window).unbind("blur");
}
Back to step 3:
My sucess method in the callback to my getviewfunction is identical to what i execute in the beginning
code:
$(".updatelatest")
.on("click",
function () {
var _this = $(this);
var options = {
loadTarget:"#TanksContent"
}
$.automation.worker.getView("/Tank/GetTanks",
function (data) {
$(_this).switchClass("col-md-5", "col-md-1", 1000, function() {
$(_this).addClass("hidden");
$(".search").switchClass("col-md-5", "col-md-12", 1000, "easeInOutQuad");
})
$.automation.tanks.tableInit();
$.automation.worker.bindIntervalEvent("#TanksContent", "/Tank/GetTanks", function () {
$.automation.tanks.tableInit();
});
$(window).trigger("blur");
}, options);
});
but this does not start the interval. it is clearly initialized since it works when window.blur is executed for example when I change tab but for some reason this is not working beyond that.
i tried triggering the windows blur event and nothing happened, i tried triggering my custom window event "focuse.mine" but nothing happens.
I did not notice this while developing since I had firebug open and every time i checked scripts or css or the console the blur function was executed so I assumed that my code worked as intended but now that it is deployed I notice this.
My head is pounding beyond reason and I can't for figure out where I have gone wrong.
Well this was a fun one. I simply found that when calling the setUpdateInterval(); function directly it gave me the desiered result.
I realized that the reason I had them split like I did was becaouse of the blur event. "Focus.mine" is triggered to start the inteval again ocne a user comes back to the page.

Prevent calling ajax on scroll when already called

I have a plugin that tells me if an element is visible in the viewport with $('#element').visible() (set to true when visible).
Now I want to create a function that I scroll down a page and load new content with ajax. I have this so far:
window.onscroll = function() {
console.log($('#ele').visible());
if ($('#ele').visible()) {
//ajax call comes here
}
};
As soon as I see the element my log shows true:
I don't have problems implementing the ajax-request now, but shouldn't I block this function to occur only once? How could I prevent that a new element that already has been loaded to load again (prevent using ajax again)?
I thought of using a boolean-variable, but my problem is that I don't know how to implement that because if I set a variable, how would the browser know it's value? Because on every move of my mousewheel it cant remember what that variable's value was?
EDIT:
I tried the code of Ismail and it never reaches the ajax call (alert won't show).
window.onscroll = function() {
var ajaxExecuted = false;
var ele = $('#load_more').visible();
console.log(ele);
return function() {
if (ajaxExecuted) return;
if (ele) {
alert("OK");
var ajaxArray;
ajaxArray = { page: 2 }
ajaxLoadContent(ajaxArray, "load_more", "ajax_load");
ajaxExecuted = true;
}
}
};
You can use this:
window.onscroll = (function() {
var ajaxExecuted = false;
return function() {
if(ajaxExecuted) return;
if ($('#ele').visible()) {
$.ajax({...}).success(function() {
//Your code here;
ajaxExecuted = true;
});
}
}
})();
One easy solution: set a boolean to true when the element first becomes visible and set it to false when it stops being visible. Only fire the request if those states mismatch (i.e. if it's visible but the boolean is false - that means it's the first time you've seen the window. You'd then set the bool afterwards so it won't fire off anymore until it disappears and reappears again).

update a page only when there are no mouse events

I would like to update the page only when there are no mouse events,
Such as:
function TimedRefresh(t) {
$('#colorbox').mousemove(event) {
if (mousemove != 0) { //(mousemove == false)
setTimeout("location.reload(false);", t);
}
}
}
It of course does not work. It's called by:
<body onload="JavaScript:TimedRefresh(5000);">
You'd do that like this
$('#colorbox').mousemove(function( event ) {
clearTimeout( $(this).data('timer') );
$(this).data('timer', setTimeout(function() {
window.location.reload();
}, 5000));
});
When the mouse moves within the #colorbox element, the timer is reset, and if no mouse movement is detected, it reloads the page in 5 seconds.
FIDDLE
You need to reverse the logic. Set the timer onload of the page and then clear/restart it when the mouse is moved. If the mouse is not moved for longer than 5 seconds, then the page will refresh:
$(document).ready(function() {
var timer;
resetTimer();
$('#colorbox').mousemove(function() {
resetTimer(timer);
});
function resetTimer() {
clearTimeout(timer);
timer = setTimeout(function() {
window.location.reload(false);
}, 5000);
}
});
Working example
I think you should do something likes this:
Create a hidden field with a default value (maybe 0).
When some MouseEvent is triggered then yo should change the value of the hidden field (maybe 1)
Then, for other side I think you could use a function like setTimeout for comparing and refresing your page. Here you can read more about this function

setTimeout function if user not active

I can do something such as the following every 30 seconds to reload the page, and the backend logic will determine which session have been invalidated:
setInterval(function () {
location.reload()
}, 30000);
However, how would I only run this 30s location.reload() if the user is not active? For example, how banks will have a user-timeout if the user has not been active on the page (which only starts counting after the user is 'inactive'). How would this be done?
One way is to track mousemoves. If the user has taken focus away from the page, or lost interest, there will usually be no mouse activity:
(function() {
var lastMove = Date.now();
document.onmousemove = function() {
lastMove = Date.now();
}
setInterval(function() {
var diff = Date.now() - lastMove;
if (diff > 1000) {
console.log('Inactive for ' + diff + ' ms');
}
}, 1000);
}());
First define what "active" means. "Active" means probably, sending a mouse click and a keystroke.
Then, design your own handler for these situations, something like this:
// Reseting the reload timer
MyActivityWatchdog.prototype.resetReloadTimer = function(event) {
var reloadTimeInterval = 30000;
var timerId = null;
...
if (timerId) {
window.clearInterval(timerId);
}
timerId = window.setInterval( reload... , reloadTimeInterval);
...
};
Then, make sure the necessary event handler will call resetReloadTimer(). For that, you have to look what your software already does. Are there key press handlers? Are there mouse movement handlers? Without knowing your code, registering keypress or mousemove on document or window and could be a good start:
window.onmousemove = function() {
...
activityWatchdog.resetReloadTimer();
...
};
But like this, be prepared that child elements like buttons etc. won't fire the event, and that there are already different event handlers. The compromise will be finding a good set of elements with registered handlers that makes sure "active" will be recognized. E.g. if you have a big rich text editor in your application, it may be enough to register only there. So maybe you can just add the call to resetReloadTimer() to the code there.
To solve the problem, use window blur and focus, if the person is not there for 30 seconds ,it will go in the else condition otherwise it will reload the page .
setTimeout(function(){
$(window).on("blur focus", function(e) {
var prevType = $(this).data("prevType");
if (prevType != e.type) { // reduce double fire issues
switch (e.type) {
case "blur":
$('div').text("user is not active on page ");
break;
case "focus":
location.reload()
break;
}
}
$(this).data("prevType", e.type);
})},30000);
DEMO : http://jsfiddle.net/rpawdg6w/2/
You can check user Session in a background , for example send AJAX call every 30 - 60 seconds. And if AJAX's response will be insufficient (e.g. Session expired) then you can reload the page.
var timer;
function checkSession() {
$.ajax({
url : 'checksession.php',
success: function(response) {
if (response == false) {
location.reload();
}
}
});
clearTimeout(timer);
timer = setTimeout(checkSession,30 * 1000);
}
checkSession();

Infinite scroll fired twice on refresh from the bottom of page

I have an infinite scroll set up with the following piece of code.
$(window).scroll(function () {
if ($(window).scrollTop() >= $("#home_content").height() - $(window).height()) {
if (isLastPage) {
foo();
} else {
bar(); // JQuery AJAX call
}
}
});
This is inside document.ready();
The ajax call doesn't happen when the server sends a flag for the last page. This works fine in a normal scenario. But when I press F5(Refresh) from the bottom of the page, two simultaneous scroll events are fired,and it bypasses the flag (as the second call happens even before the flag is set) and duplicate data is loaded.
The only thing i know is it happens at the end of document.ready() function. Anyone, any idea??
Thanks in advance.
EDIT
There is no much relevant code other than this.
And this happens only in FF 17.
In IE 9 when I do a fast scroll down, same scroll is fired twice
You can use this debounce routine for all sort of event calls. Clean and reusable.
// action takes place here.
function infinite_scrolling(){
if ($(window).scrollTop() >= $("#home_content").height() - $(window).height()) {
if (isLastPage) {
foo();
} else {
bar(); // JQuery AJAX call
}
}
}
// debounce multiple requests
var _scheduledRequest = null;
function infinite_scroll_debouncer(callback_to_run, debounce_time) {
debounce_time = typeof debounce_time !== 'undefined' ? debounce_time : 800;
if (_scheduledRequest) {
clearTimeout(_scheduledRequest);
}
_scheduledRequest = setTimeout(callback_to_run, debounce_time);
}
// usage
$(document).ready(function() {
$(window).scroll(function() {
infinite_scroll_debouncer(infinite_scrolling, 1000);
});
});
This is just a workaround as we cannot see your complete code, but maybe thats can help:
var timeout;
$(window).scroll(function(){
clearTimeout(timeout);
timeout = setTimeout(function(){
if ($(window).scrollTop() >= $("#home_content").height() - $(window).height()){
if (isLastPage){
foo();
}else{
bar();//AJAX call
}
}
},0);
});

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