I'm learning with Titanium to make iPhone/Android apps. I'm using Alloy MVC framework. I never used javascript before, apart from simple scripts in HTML to access the DOM or something like that, so I never needed to structure the code before.
Now, with Titanium, I must use a lot of JS code and I was looking for ways to structure my code. Basically I found 3 ways to do it: prototype, namespace and functions inside functions.
Simple example for each:
Prototype:
NavigationController = function() {
this.windowStack = [];
};
NavigationController.prototype.open = function(windowToOpen) {
//add the window to the stack of windows managed by the controller
this.windowStack.push(windowToOpen);
//grab a copy of the current nav controller for use in the callback
var that = this;
windowToOpen.addEventListener('close', function() {
if (that.windowStack.length > 1)
{
that.windowStack.pop();
}
});
if(Ti.Platform.osname === 'android') {
windowToOpen.open();
} else {
this.navGroup.open(windowToOpen);
}
};
NavigationController.prototype.back = function(w) {
//store a copy of all the current windows on the stack
if(Ti.Platform.osname === 'android') {
w.close();
} else {
this.navGroup.close(w);
}
};
module.exports = NavigationController;
Using it as:
var NavigationController = require('navigator');
var navController = new NavigationController();
Namespace (or I think is something like that, coz the use of me = {}):
exports.createNavigatorGroup = function() {
var me = {};
if (OS_IOS) {
var navGroup = Titanium.UI.iPhone.createNavigationGroup();
var winNav = Titanium.UI.createWindow();
winNav.add(navGroup);
me.open = function(win) {
if (!navGroup.window) {
// First time call, add the window to the navigator and open the navigator window
navGroup.window = win;
winNav.open();
} else {
// All other calls, open the window through the navigator
navGroup.open(win);
}
};
me.setRightButton = function(win, button) {
win.setRightNavButton(button);
};
me.close = function(win) {
if (navGroup.window) {
// Close the window on this nav
navGroup.close(win);
}
};
};
return me;
};
Using it as:
var ui = require('navigation');
var nav = ui.createNavigatorGroup();
Functions inside functions:
function foobar(){
this.foo = function(){
console.log('Hello foo');
}
this.bar = function(){
console.log('Hello bar');
}
}
// expose foobar to other modules
exports.foobar = foobar;
Using it as:
var foobar = require('foobar').foobar
var test = new foobar();
test.bar(); // 'Hello bar'
And now my question is: which is the better to maintain code clean and clear? It seems that prototype is clear an easy to read/mantain. Namespace confuses me a bit but only needs to execute the initial function to be "available" (no use of new while declaring it, I suppose because it returns the object?namespace? "me"). Finally, functions inside functions is similar to the last, so I don't know exactly the difference, but is useful to export only the main function and have all the inside functions available for use it later.
Maybe the last two possibilities are the same, and I'm messing concepts.
Remember that I'm searching for a good way to structure the code and have functions available to other modules and also inside the own module.
I appreciate any clarification.
In the examples that they release, Appcelerator appears to follow the non-prototype approach. You can see it in the examples they have released: https://github.com/appcelerator/Field-Service-App.
I've seen a lot of different approaches to structuring applications in Titanium before Alloy. Since Alloy, I've found following the development team's examples helpful to me.
With that being said, it seems to me that all of this is still under interpretation and open to change and community development. Before Alloy there were some great community suggestions on structuring an app and I believe that it is still open with Alloy. Often when I find someone's example code I see something they did with it that appears to organize it a bit better than I thought of. It seems to make it a bit easier.
I think you should structure your application in a way that makes sense to you. You may stumble on to a better and easier way of developing applications with Alloy, because you are looking at it critically.
I haven't found a lot of extensive Alloy examples, but Field-Service-App makes sense to me. They have a nice separation of the elements in the application beyond MVC. Check it out.
Related
The Problem
I just cannot figure out the view model in NativeScript
I am having a hard time understanding how view-models work in NativeScript. I understand the high level concept - that the MVVM pattern allows us to create observable objects - and our UI is updated when values change.
Here is a simple example:
main-page.js
var createViewModel = require("./main-view-model").createViewModel;
function onNavigatingTo(args) {
var page = args.object;
page.bindingContext = createViewModel();
}
exports.onNavigatingTo = onNavigatingTo;
main-view-model.js
var Observable = require("tns-core-modules/data/observable").Observable;
function getMessage(counter) {
if (counter <= 0) {
return "Hoorraaay! You unlocked the NativeScript clicker achievement!";
} else {
return counter + " taps left";
}
}
function createViewModel() {
var viewModel = new Observable();
viewModel.counter = 42;
viewModel.message = getMessage(viewModel.counter);
viewModel.onTap = function() {
this.counter--;
this.set("message", getMessage(this.counter));
}
return viewModel;
}
exports.createViewModel = createViewModel;
I understand , some what, what is happening. But not everything.
Questions I Have ...
How would you add a new function , for instance, an email validation function? Would it go into the View Model page, or just plain Javscript page?
Let's say I added a new textfield to the UI. I have a tap function. Where does my function go?
So in this case, everything related to the UI should go in the createViewModel function? Is that correct?
I have also seen in sample apps, where the developer doesn't use view models at all - it appears he just creates it as an observable object.
Thank you for looking. I know I am close to understanding, but that bindingContext and the viewmodel has me a bit confused. [ I have read everything in NS docs ]
John
The answer is either of it should work. You may put the validation or tap function in view model or in the code behind file, it's upto you to decide which works best for you.
If you put it in the view model, you will use event binding (tap="{{ functionName }}" Or if you put it in code behind file, you will just export the function name and simply refer the function name on XML (tap="functionName").
By giving this flexibility you are allowed to separate your code, keep the files light weighted.
I have a small problem.
I have index.js
var loc = require('location');
function doClick (){
loc.doIt();
}
in location.js I have these
var dee = 12;
exports.doIt = function() {
alert(dee);
};
Which means that when I click on the button I can get the alert, however, I want to reach these information without a need of click - onLoad - besides I want to return two values not only one.
How I can fix this maybe it has really an easy solution but because I have been working for a while my mind stopped working :)
regards
you should move your location.js to inside app/lib (as module). for example :
// app/lib/helper.js
exports.callAlert = function(text) {
alert('hello'+ text);
}
and then call it in your controller like this :
var helper = require("helper"); // call helper without path and .js extension
helper.callAlert('Titanium');
and your problem should be solved :)
This was originally posted on discuss.emberjs.com. See:
http://discuss.emberjs.com/t/what-is-the-proper-use-of-store-filter-store-find-for-infinite-scrolling/3798/2
but that site seems to get worse and worse as far as quality of content these days so I'm hoping StackOverflow can rescue me.
Intent: Build a page in ember with ember-data implementing infinite scrolling.
Background Knowledge: Based on the emberjs.com api docs on ember-data, specifically the store.filter and store.find methods ( see: http://emberjs.com/api/data/classes/DS.Store.html#method_filter ) I should be able to set the model hook of a route to the promise of a store filter operation. The response of the promise should be a filtered record array which is a an array of items from the store filtered by a filter function which is suppose to be constantly updated whenever new items are pushed into the store. By combining this with the store.find method which will push items into the store, the filteredRecordArray should automatically update with the new items thus updating the model and resulting in new items showing on the page.
For instance, assume we have a Questions Route, Controller and a model of type Question.
App.QuestionsRoute = Ember.Route.extend({
model: function (urlParams) {
return this.get('store').filter('question', function (q) {
return true;
});
}
});
Then we have a controller with some method that will call store.find, this could be triggered by some event/action whether it be detecting scroll events or the user explicitly clicking to load more, regardless this method would be called to load more questions.
Example:
App.QuestionsController = Ember.ArrayController.extend({
...
loadMore: function (offset) {
return this.get('store').find('question', { skip: currentOffset});
}
...
});
And the template to render the items:
...
{{#each question in controller}}
{{question.title}}
{{/each}}
...
Notice, that with this method we do NOT have to add a function to the store.find promise which explicitly calls this.get('model').pushObjects(questions); In fact, trying to do that once you have already returned a filter record array to the model does not work. Either we manage the content of the model manually, or we let ember-data do the work and I would very much like to let Ember-data do the work.
This is is a very clean API; however, it does not seem to work they way I've written it. Based on the documentation I cannot see anything wrong.
Using the Ember-Inspector tool from chrome I can see that the new questions from the second find call are loaded into the store under the 'question' type but the page does not refresh until I change routes and come back. It seems like the is simply a problem with observers, which made me think that this would be a bug in Ember-Data, but I didn't want to jump to conclusions like that until I asked to see if I'm using Ember-Data as intended.
If someone doesn't know exactly what is wrong but knows how to use store.push/pushMany to recreate this scenario in a jsbin that would also help too. I'm just not familiar with how to use the lower level methods on the store.
Help is much appreciated.
I just made this pattern work for myself, but in the "traditional" way, i.e. without using store.filter().
I managed the "loadMore" part in the router itself :
actions: {
loadMore: function () {
var model = this.controller.get('model'), route = this;
if (!this.get('loading')) {
this.set('loading', true);
this.store.find('question', {offset: model.get('length')}).then(function (records) {
model.addObjects(records);
route.set('loading', false);
});
}
}
}
Since you already tried the traditional way (from what I see in your post on discuss), it seems that the key part is to use addObjects() instead of pushObjects() as you did.
For the records, here is the relevant part of my view to trigger the loadMore action:
didInsertElement: function() {
var controller = this.get('controller');
$(window).on('scroll', function() {
if ($(window).scrollTop() > $(document).height() - ($(window).height()*2)) {
controller.send('loadMore');
}
});
},
willDestroyElement: function() {
$(window).off('scroll');
}
I am now looking to move the loading property to the controller so that I get a nice loader for the user.
I saw there is somes questions related to mine (like this interesting one), but what I wonders is how to do it correctly, and I couldn't find it via the others questions or the RequireJS documentation.
I'm working on a quite heavy web application that will run in only one html page.
Before RequireJS, I used to do a lot of JS modules with public methods and connecting them via the on event on the Dom READY method, like this :
var DataList = function () {
this.base = arguments[0];
this.onUpdate = function (event) { ... }
}
$(function () {
var dataList = {}; DataList.apply(dataList, [$('#content')]);
$('table.main', dataList.base).on ('update', dataList.onUpdate);
});
With RequireJS, I can easily see that I can split DataList and all others classes like this on individual files, but what about the $(function () {}); part?
Can I still keep it this way, but instead of the DOM ready function of jQuery, I put the events on the main function() of the RequireJS, when my primary libs are loaded?
Or do I have to change the way I create JS "classes", to include a init function maybe, that will be called when I do a, for example :
require(['Datalist'], function(dataList) {
dataList.init($('#content'));
});
What annoys me the most is that since I have only one html file, I'm afraid the require() will have to load a huge list of files, I'd prefer it to load just libs that, them, would load sub libs required to work.
I don't know, the way of thinking with RequireJS lost me a bit :/
How would you do?
"Can I still keep it this way, but instead of the DOM ready function of jQuery, I put the events on the main function() of the RequireJS, when my primary libs are loaded?"
If you separate the functions or 'classes' into modules then you can use the RequireJS domReady function:
require(['module1'], function(module1) {
domReady(function(){
// Some code here ftw
})
});
The benefit here is the domReady function will allow downloading of the modules instantly but won't execute them until your DOM is ready to go.
"Or do I have to change the way I create JS "classes", to include a init function maybe, that will be called when I do a, for example"
You won't need to change the way you interact with your code this way, but you can probably improve it. In your example I would make DataList a module:
define(function(require) {
var $ = require('jquery');
var DataList = function () {
this.base = arguments[0];
};
DataList.prototype.onUpdate = function() {
};
return DataList;
});
require(['data-list'], function(DataList) {
var data = {};
// Call DataList with new and you won't need to set the context with apply
// otherwise it can be used exactly as your example
new DataList(data);
});
"What annoys me the most is that since I have only one html file, I'm afraid the require() will have to load a huge list of files, I'd prefer it to load just libs that, them, would load sub libs required to work."
Make your code as modular as you want/can and then use the optimiser to package it into one JS file.
Is it possible to detect when a user is printing something from their browser?
To complicate matters, if we are presenting a user with a PDF document in a new window is it possible to detect the printing of that document ( assuming the user prints it from the browser window)?
The closest I've been able to find is if we implement custom print functionality (something like this) and track when that is invoked
I'm primarily interested in a solution that works for internet explorer (6 or later)
You can now detect a print request in IE 5+, Firefox 6+, Chrome 9+, and Safari 5+ using the following technique:
(function() {
var beforePrint = function() {
console.log('Functionality to run before printing.');
};
var afterPrint = function() {
console.log('Functionality to run after printing');
};
if (window.matchMedia) {
var mediaQueryList = window.matchMedia('print');
mediaQueryList.addListener(function(mql) {
if (mql.matches) {
beforePrint();
} else {
afterPrint();
}
});
}
window.onbeforeprint = beforePrint;
window.onafterprint = afterPrint;
}());
I go into more detail into what this is doing and what it can be used for at http://tjvantoll.com/2012/06/15/detecting-print-requests-with-javascript/.
For Internet Exploder, there are the events window.onbeforeprint and window.onafterprint but they don't work with any other browser and as a result they are usually useless.
They seem to work exactly the same for some reason, both executing their event handlers before the printing window opens.
But in case you want it anyway despite these caveats, here's an example:
window.onbeforeprint = function() {
alert("Printing shall commence!");
}
For anyone reading this on 2020.
The addListener function is mostly deprecated in favor of addEventListener except for Safari:
if (window.matchMedia) {
const media = window.matchMedia("print");
const myFunc = mediaQueryList => {
if (mediaQueryList.matches) {
doStuff();
}
};
try {
media.addEventListener("change", myFunc);
} catch (error) {
try {
media.addListener(myFunc);
} catch (error) {
console.debug('Error', error)
}
}
}
Reference: This other S.O question
If it's only for tracking purposes, perhaps you could set a background url in CSS print media to a server page (.aspx, .php, etc) and then do something on the server?
This guy claims it works.
This is not as versitile as TJ's solution, but it may be less buggy (see TJs blog post for issues he found) when only tracking is needed.