I am attempting to re-create the solution seen here for keeping a session alive by using an HTTPHandler and making an AJAX call to it.
The solution does not appear to have worked, and when I tried to debug it by adding an alert(); just before the $.get(); the alert(); never got fired off. I copied and pasted the code from the example, so I'm not missing a semicolon or something. I even set an alert(); before the setTimeout(); and that one worked!
function setHeartbeat() {
alert("I get here!");
setTimeout("heartbeat()", 300000); // every 5 min
}
function heartbeat() {
alert("I never seem to fire off!");
$.get(
"/SessionHeartbeat.ashx",
null,
function(data) {
setHeartbeat();
},
"json"
);
}
Any thoughts?
Both slon and Hans Kesting were right one the money.
The working javascript is:
$(document).ready(function () {
//alert("Document is ready.");
// set the initial call
setHeartbeat();
function setHeartbeat() {
//alert("setHeartbeat");
setInterval(function () {
heartbeat();
}, 10000); // every 10 sec
}
function heartbeat() {
//alert("heartbeat");
$.get(
"/SessionHeartbeat.ashx",
null,
function(data) {
setHeartbeat();
},
"json"
);
}
});
Thank you both!
Related
Router.route('/courses/:_catalog', function () {
var courseCatalog = this.params._catalog.toUpperCase();
Meteor.subscribe("courseCatalog", courseCatalog);
this.render('CourseDetail', {
to: 'content',
data: function () {
return Courses.findOne({catalog: courseCatalog});
}
});
}, {
onAfterAction: function() {
if (!Meteor.isClient) {
return;
}
debugger
var course = this.data(); <======
SEO.set({
title: "course.catalog"
});
}
});
In the above code, please look at the debugger statement. I want to access the data but it seems I am doing something wrong because this.data doesn't exist. I also tried Courses.find().fetch() but I only get an empty array inside onAfterAction. What's the right syntax and what am I missing?
It needs to be inside a this.ready() block:
onAfterAction: function() {
if (this.ready()) {
var course = this.data();
...
}
}
You need to subscribe to data first. Have a look at the waitOn function to do this. The server only sends the documents you subscribed to, and since you didn't subscribe, Courses.find().fetch() returns an empty array.
Also, don't put SEO stuff in onAfterAction. Put it in onRun which is guaranteed to only run once.
This is a bit puzzling to me. I set data in the router (which I'm using very simply intentionally at this stage of my project), as follows :
Router.route('/groups/:_id',function() {
this.render('groupPage', {
data : function() {
return Groups.findOne({_id : this.params._id});
}
}, { sort : {time: -1} } );
});
The data you would expect, is now available in the template helpers, but if I have a look at 'this' in the rendered function its null
Template.groupPage.rendered = function() {
console.log(this);
};
I'd love to understand why (presuming its an expected result), or If its something I'm doing / not doing that causes this?
From my experience, this isn't uncommon. Below is how I handle it in my routes.
From what I understand, the template gets rendered client-side while the client is subscribing, so the null is actually what data is available.
Once the client recieves data from the subscription (server), it is added to the collection which causes the template to re-render.
Below is the pattern I use for routes. Notice the if(!this.ready()) return;
which handles the no data situation.
Router.route('landing', {
path: '/b/:b/:brandId/:template',
onAfterAction: function() {
if (this.title) document.title = this.title;
},
data: function() {
if(!this.ready()) return;
var brand = Brands.findOne(this.params.brandId);
if (!brand) return false;
this.title = brand.title;
return brand;
},
waitOn: function() {
return [
Meteor.subscribe('landingPageByBrandId', this.params.brandId),
Meteor.subscribe('myProfile'), // For verification
];
},
});
Issue
I was experiencing this myself today. I believe that there is a race condition between the Template.rendered callback and the iron router data function. I have since raised a question as an IronRouter issue on github to deal with the core issue.
In the meantime, workarounds:
Option 1: Wrap your code in a window.setTimeout()
Template.groupPage.rendered = function() {
var data_context = this.data;
window.setTimeout(function() {
console.log(data_context);
}, 100);
};
Option 2: Wrap your code in a this.autorun()
Template.groupPage.rendered = function() {
var data_context = this.data;
this.autorun(function() {
console.log(data_context);
});
};
Note: in this option, the function will run every time that the template's data context changes! The autorun will be destroyed along with the template though, unlike Tracker.autorun calls.
i want to disable a button for a specific time. how can i do that?
Since this is likely to be a task you might like to repeat, I think the best way to do this would be to extend jQuery like so:
$.fn.timedDisable = function(time) {
if (time == null) { time = 5000; }
return $(this).each(function() {
$(this).attr('disabled', 'disabled');
var disabledElem = $(this);
setTimeout(function() {
disabledElem.removeAttr('disabled');
}, time);
});
};
This will allow you to call a function on a set of matched elements which will temporarily disable them. As it is written, you can simply call the function, and the selected elements will be disabled for 5 seconds. You would do that like so:
$('#some-button').timedDisable();
You can adjust the default time setting by changing the 5000 in the following line:
if (time == null) { time = 5000; }
You can optionally pass in a time value in milliseconds to control how long the elements will be disabled for. For example:
$('#some-button').timedDisable(1000);
Here's a working demo: http://jsfiddle.net/fG2ES/
Disable the button and then use setTimeout to run a function that enables the button after a few seconds.
$('#some-button').attr("disabled", "disabled");
setTimeout('enableButton()', 5000);
function enableButton(){
$('#some-button').removeAttr('disabled');
}
Try this.
(function(){
$('button').on('click',function(){
var $this=$(this);
$this
.attr('disabled','disabled');
setTimeout(function() {
$this.removeAttr('disabled');
}, 3000);
});
})();
You can find a working example here http://jsfiddle.net/informativejavascript/AMqb5/
Might not be the most elegant solution, but I thought I'd play with jQuery queues on this one...
$.fn.disableFor = function (time) {
var el = this, qname = 'disqueue';
el.queue(qname, function () {
el.attr('disabled', 'disabled');
setTimeout( function () {
el.dequeue(qname);
}, time || 3000);
})
.queue(qname, function () {
el.removeAttr('disabled');
})
.dequeue(qname);
};
$('#btn').click( function () {
$(this).disableFor(2000);
});
This is where I worked it out... http://jsfiddle.net/T9QJM/
And, for reference, How do I chain or queue custom functions using JQuery?
I have the code below that shows a throbber and makes a getJSON call to an MVC action when the user changes an entry in a select. This all works great except there is a default -- select -- element in the list for which I don't want the getJSON to run.
However, I can't work out how to apply conditional logic to hooking this event. The conditional logic is shown as the if(selectedValue == -1) But the throbber still runs as I've hooked it in the first line. I've tried removing the first line that hooks the change event and use $.throbberShow(..) inline just prior to the getJSON call but for some reason this doesn't show the throbber.
Any help greatly appreciated.
$("#selectlist").throbber("change", { ajax: false, image: "images/ajax-loader-line.gif" });
$("#selectlist").change(
function () {
var selectedValue = $("#selectlist").val();
if (selectedValue != -1) {
//Tried doing $.throbberShow(...) here without success
$.getJSON("/Candidate/GetAddress", { id: selectedValue }, function (data, textStatus) {
if (textStatus == "success") {
$("#selectlist").val(data.Line1)
$("#selectlist").val(data.Line2)
$("#selectlist").val(data.Line3)
$("#selectlist").val(data.Town)
}
$.throbberHide();
});
}
}
);
It is more a hack than a solution as throbber doesn't support conditions but this should work:
$("#selectlist").throbber("change", { ajax: false, image: "images/ajax-loader-line.gif", delay: "500" });
$("#selectlist").change(
function () {
var selectedValue = $("#selectlist").val();
if (selectedValue != -1) {
$.getJSON("/Candidate/GetAddress", { id: selectedValue }, function (data, textStatus) {
if (textStatus == "success") {
$("#selectlist").val(data.Line1)
$("#selectlist").val(data.Line2)
$("#selectlist").val(data.Line3)
$("#selectlist").val(data.Town)
}
$.throbberHide();
});
} else {
$.throbberHide();
}
}
);
I don't know why but this code is not working ? Why would it not ? I guess it is because scope problem I am having here :
function washAway(obj) {
alert($(obj)); // says HTML Object which is fine
setTimeout(function() {
alert($(obj)); // says undefined
$(obj).fadeOut("slow", function() {
$(this).remove();
});
}, 2000);
};
At the point where the function in the timeout executes, it has no way to know what obj is - it was a parameter passed into the method where the timeout was set up, but the function inside has no reference to it.
An alternative approach is to write a jQuery plugin to wait before it acts like this:
function($){ //to protect $ from noConflict()
$.fn.pause = function(duration) {
$(this).animate({ dummy: 1 }, duration);
return this;
};
}
Then you can use:
$(obj).pause(2000).fadeOut("slow", function() { $(this).remove(); });
Any ways, I've found my answer after a couple of try/wrong. But I am still wondering why it didn't work out.
Here is the code :
function washAway(obj) {
alert($(obj).attr("id"));
var a = function() {
var _obj = obj;
return function() {
$(_obj).fadeOut("slow", function() {
$(this).remove();
});
};
};
setTimeout(a(), 2000);
};
Edit : I think I understood the problem here :
Because we are talking about closures here, when washAway execution finishes, the variable obj is destroyed so setTimeOut function callback function can't use that resource because it is no more available on the stack and it is not also a global variable.