Even though I've been using mootools for a while now, I haven't really gotten into playing with the natives yet. Currently I'm trying to extend events by adding a custom addEvent method beside the original. I did that using the following code(copied from mootools core)
Native.implement([Element, Window, Document], {
addMyEvent:function(){/* code here */}
}
Now the problem is that I can't seem to figure out, how to properly overwrite the existing fireEvent method in a way that I can still call the orignal method after executing my own logic.
I could probably get the desired results with some ugly hacks but I'd prefer learning the elegant way :)
Update: Tried a couple of ugly hacks. None of them worked. Either I don't understand closures or I'm tweaking the wrong place. I tried saving Element.fireEvent to a temporary variable(with and without using closures), which I would then call from the overwritten fireEvent function(overwritten using Native.implement - the same as above). The result is an endless loop with fireEvent calling itself over and over again.
Update 2:
I followed the execution using firebug and it lead me to Native.genericize, which seems to act as a kind of proxy for the methods of native classes. So instead of referencing the actual fireEvent method, I referenced the proxy and that caused the infinite loop. Google didn't find any useful documentation about this and I'm a little wary about poking around under the hood when I don't completely understand how it works, so any help is much appreciated.
Update 3 - Original problem solved:
As I replied to Dimitar's comment below, I managed to solve the original problem by myself. I was trying to make a method for adding events that destroy themselves after a certain amount of executions. Although the original problem is solved, my question about extending natives remain.
Here's the finished code:
Native.implement([Element, Window, Document], {
addVolatileEvent:function(type,fn,counter,internal){
if(!counter)
counter=1;
var volatileFn=function(){
fn.run(arguments);
counter-=1;
if(counter<1)
{
this.removeEvent(type,volatileFn);
}
}
this.addEvent(type,volatileFn,internal);
}
});
is the name right? That's the best I could come up with my limited vocabulary.
document.id("clicker").addEvents({
"boobies": function() {
console.info("nipple police");
this.store("boobies", (this.retrieve("boobies")) ? this.retrieve("boobies") + 1 : 1);
if (this.retrieve("boobies") == 5)
this.removeEvents("boobies");
},
"click": function() {
// original function can callback boobies "even"
this.fireEvent("boobies");
// do usual stuff.
}
});
adding a simple event handler that counts the number of iterations it has gone through and then self-destroys.
think of events as simple callbacks under a particular key, some of which are bound to particular events that get fired up.
using element storage is always advisable if possible - it allows you to share data on the same element between different scopes w/o complex punctures or global variables.
Natives should not be modded like so, just do:
Element.implement({
newMethod: function() {
// this being the element
return this;
}
});
document.id("clicker").newMethod();
unless, of course, you need to define something that applies to window or document as well.
Related
It seems that most people I read about experence zero trouble with this. I, on the other hand, have a test suite which someone else wrote, in which I'm trying to replace route() with intercept(). The API intercepts are done to handle button clicks etc., and about 99.9% percent of them fails if I just replace it. So, there's obviously some syntax in/use of intercept() I've not found a description for.
Example:
This works:
cy.route('POST', getApiPrefix() + '/prosjektfinansiering/'+ pfId +'/eiendom', result);
This does not work. The button click is not executed:
cy.intercept('POST', getApiPrefix() + '/prosjektfinansiering/'+ pfId +'/eiendom', result);
I've tried adding '**' in front of "/prosjekt...", and I've tried removing 'POST', with no luck.
Any ideas? I'll gladly post more info if necessary.
UPDATE:
Futher attempts:
Getting some hints here and there, it seems that this is a more correct way of using intercept():
return cy.intercept('POST', getApiPrefix() + '/prosjektfinansiering/'+ pfId +'/eiendom', {
body: result
});
This doesn't work, either.
The variables result in these examples is an object describing what is sent back to the frontend of the POST-request in the route matches the api path.
For troubleshooting, I can see that when using intercept(), there is ONE route that is not working when using intercept (the bottom one in the picture). However, I cannot for the life of me see why, and how the route match can be written differently?
Most likely, you're mixing the old use of cy.route() and cy.server(). In my experience, those two won't work well together. It's easier when you're starting fresh with just cy.intercept().
Your update is correct too; You have to encapsulate the return value you want mocked in {body: value}.
from what I am seeing in your circled screenshot, the API is not called after you try to intercept it. (the count under # column is -)
You need to track when the API is to be called and ensure you intercept before the call is made. Cypres can help you with this. You can go through the run steps in the cypress window.
You could also share this if you don't mind.
If you are 100% certain the button makes the call. Steps should be:
cy.intercept()
cy.get('button').click()
In the cypress window, right after the click, you should see the API being called.
Why is ReactiveList with ChangeTrackingEnabled slow when I Clear inside SuppressChangeNotifications?
With 10,000 entries it takes about 2 seconds for the Clear method to return.
Shouldn't SuppressChangeNotifications bypass the change tracking code?
Or how can I improve the performance here?
ReactiveList<Person> _personList = new ReactiveList<Person> { ChangeTrackingEnabled = true };
using (_personList.SuppressChangeNotifications())
{
_personList.Clear();
}
Thanks a lot.
Change tracking code is bypassed, but still ReactiveList needs to cleanup its internal stuff when you clear the list. And the method used to do so is extremely inefficient ( O(n2) ), as detailed in this SO answer.
The Clear implementation with change tracking enabled can definitely be improved, I'll send a PR to RxUI if I get the chance.
E.g. replacing this code by foreach (var foo in _propertyChangeWatchers.Values.ToList()) foo.Release(); makes the Clear immediate, w/o altering the behavior.
EDIT :
You can work around this performance issue by writing instead:
using (_personList.SuppressChangeNotifications())
_personList.RemoveRange(0, _personList.Count);
Good day!
I began writing my own basic JavaScript library for personal use and distribution a few days ago, but I am having trouble with one of the methods, specifically bind().
Within the method itself, this refers to the library, the object.
I went to Google and found function.call(), but it didn't work out the way I planned it--it just executed the function.
If you take a look at another method, each(), you'll see that it uses call() to pass values.
I also tried the following:
f.arguments[0]=this;
My console throws an error, saying it cannot read '0' of "undefined".
I would like to be able to pass this (referencing the library--NOT THE WINDOW) to use it in the event listener.
You can see it starting at line 195 of the JavaScript of this JSFiddle.
Here it is as well:
bind:function(e,f){
if(e.indexOf("on")==0){
e=e.replace("on","");
}
if(typeof f==='function'){
/*Right now, 'this' refers to the library
How can I pass the library to the upcoming eventListener?
*/
//f=f(this); doesn't work
//f.call(this); //doesn't work
//this.target refers to the HTMLElement Object itself, which we are adding the eventListener to
//the outcome I'm looking for is something like this:
/*$('h3').which(0).bind(function({
this.css("color:red");
});*/
//(which() defines which H3 element we're dealing with
//bind is to add an event listener
this.target.addEventListener(e,f,false)
}
return this;
},
Thank you so much for your help, contributors!
If, as per your comments, you don't want to use .bind(), rather than directly passing f to addEventListener() you could pass another function that in turn calls f with .call() or .apply():
if(typeof f==='function'){
var _this = this;
this.target.addEventListener(e,function(event){
f.call(_this, event);
},false)
}
Doing it this way also lets your library do any extra event admin, e.g., pre-processing on the event object to normalise properties that are different for different browsers.
So in this particular case you actually want to call JavaScript's built in bind method that all functions have.
f = f.bind(this);
f will be a new function with it's this argument set to whatever you passed into it.
Replace f=f(this); with f.apply(this);
Look at underscore code, here:
https://github.com/jashkenas/underscore/blob/master/underscore.js#L596
So, I was attempting to do something like the following:
if(Meteor.isServer){
Meteor.methods({connect_to_api: function(vars){
// get data from remote API
return data;
}});
}
if(Meteor.isClient){
Template.myTpl.content = function(){
Meteor.call('connect_to_api', vars, function(err,data){
Session.set('placeholder', data);
});
return Session.get('placeholder');
};
}
This seemed to be working fine, but, of course, now breaks in 0.5.9 as the Session object has been removed from the server. How in the world do you now create a reactive Template that uses a server-only (stuff we don't want loading on the client) method call and get data back from that Method call. You can't put any Session references in the callback function because it doesn't exist on the server, and I don't know of any other reactive data sources available for this scenario.
I'm pretty new to Meteor, so I'm really trying to pin down best-practices stuff that has the best chance of being future-proof. Apparently the above implementation was not it.
EDIT: To clarify, this is not a problem of when I'm returning from the Template function. This is a problem of Session existing on the server. The above code will generate the following error message on the server:
Exception while invoking method 'connect_to_api' ReferenceError: Session is not defined
at Meteor.methods.connect_to_api (path/to/file.js:#:#)
at _.extend.protocol_handlers.method.exception ... etc etc
Setting the session in the callback seems to work fine, see this project I created on github: https://github.com/jtblin/meteor_session_test. In this example, I return data in a server method, and set it in the session in the callback.
There are 2 issues with your code:
1) Missing closing brace placement in Meteor.methods. The code should be:
Meteor.methods({
connect_to_api: function(vars) {
// get data from remote API
return data;
}
});
2) As explained above, you return the value in the session, before the callback is completed, i.e. before the callback method had the time to set the session variable. I guess this is why you don't see any data in the session variable yet.
I feel like an idiot (not the first time, not the last). Thanks to jtblin for showing me that Session.set does indeed work in the callback, I went back and scoured my Meteor.method function. Turns out there was one spot buried in the code where I was using Session.get which was what was throwing the error. Once I passed that value in from the client rather than trying to get it in the method itself, all was right with the world.
Oh, and you can indeed order things as above without issue.
Using JQuery.load(), I change the content of my website's mainWindow to allow the user to switch between tabs. For each tab, there is one or multiple scipts that contain functions that are executed once the tab content is loaded.
Obviously when switching to the tab for the first time, the script has to be fetched from the server and interpreted, but this shouldn't happen if the user switches back to the tab later on. So, to put it short:
Load() html
make sure javascript functions exist, otherwise load script and interpret it.
call a a function on the javascript after the DOM is rebuilt.
Step one and two have to be complete before step 3 is performed.
At the moment, I am using nested callbacks to realize this:
function openFirstTab(){
$("#mainWindow").load("firstTab.php", function(){
if(typeof(onloadfFirstTab) != "function"){
jQuery.getScript("assets/js/FirstTab.js", function(){
onloadFirstTab();
});
}
else{
onloadFirstTab();
}
} );
}
but I feel that there should be a better way.
You can't write the code entirely synchronously since you can't load script synchronously after page load ( unless you do a synchronous XHR request and eval the results - not recommended ).
You've got a couple of choices. There are pre-existing dependency management libs like RequireJS which may fit the bill here, or if you just need to load a single file you can do something like this to clean up your code a bit rather than using if/else:
function loadDependencies() {
// For the sake of example, the script adds "superplugin" to the jQuery prototype
return $.getScript( "http://mysite.com/jquery.superplugin.js" );
}
function action() {
// If superplugin hasn't been loaded yet, then load it
$.when( jQuery.fn.superplugin || loadDependencies() ).done(function() {
// Your dependencies are loaded now
});
}
This makes use of jQuery Deferreds/Promises to make the code much nicer.
If you don't want to load the JS more than once and you are going to dynamically load it, then the only way to know whether it's already loaded is to test for some condition that indicates it has already been loaded. The choices I'm aware of are:
The simplest I know of is what you are already doing (check for the existence of a function that is defined in the javascript).
You could also use a property on each tab (using jQuery's .data() that you set to true after you load the script.
You could write the dynamically loaded code so that it knows how to avoid re-initializing itself if it has already been loaded. In that case, you just load it each time, but the successive times don't do anything. Hint, you can't have any statically defined globals and you have to test if it's already been loaded before it runs its own initialization code.
(Haven't tested it yet, so I am not sure if it works, especially since I didn't yet really understand scope in javascript:)
function require(scripts, callback){
var loadCount = 0;
function done(){
loadCount -=1;
if (loadCount==0){
callback();
}
}
for ( var script in scripts){
if (!script.exitsts()){
loadCount +=1;
jQuery.getScript(script.url, done);
}
}
}
This function takes an array of scripts that are required and makes sure all of them are interpreted before it calls the callback().
The "script" class:
function script(url, testFunc){
this.url =url;
this.testFunction = testFunc;
this.exists = function(){
if(typeof(testFunction)=="function"){
return true;
}
else{
return false;
}
}
}
Where the test-function is a function that is defined (only) in the concerned script.
PS:
To enable caching in JQuery and thus prevent the browser from doing a GET request every time getScript() is called, you can use one of the methods that are presented here.
Even though unnecessary GET - requests are avoided, the script is still getting interpreted every time getScript() is called. This might sometimes be the desired behavior. But in many cases, there is no need to re-interpret library functions. In these cases it makes sense to avoid calling getScript() if the required library functions are already available. (As it is done in this example with script.exists().