Develop Reference

Errors when using 'ControllerAs' but works fine when using '$scope' in ng-repeat checkbox

When using '$scope' syntax, checking on individual checkbox correctly outputs its corresponding object name but when applying 'ControllerAs' syntax to same code, checking on individual checkbox abnormally generates error
$scope.users = [{.....}] //using $scope syntax
$scope.selected = [];
$scope.exist = function(item) {
return $scope.selected.indexOf(item) > -1;
}
$scope.toggleSelection = function(item) {
var idx = $scope.selected.indexOf(item);
if (idx > -1) {
$scope.selected.splice(idx, 1);
} else {
$scope.selected.push(item);
}
}
Representation of above code using in ControllerAs
vm.users = [{....}] //Using 'Controller As' Syntax
vm.selected = [];
vm.exist = function(item) {
return vm.selected.indexOf(item) > -1;
}
vm.toggleSelection = function(item) {
var idx = vm.selected.indexOf(item);
if (idx > -1) {
vm.selected.splice(idx, 1);
} else {
vm.selected.push(item);
}
}
Error returned in chrome developer tools
TypeError: vm.selected.indexOf is not a function
at GridController.vm.exist (gridController.js:37)
Demo Controller As, http://plnkr.co/edit/5auLDGbpyDFUcpPxBzNs?p=preview
Demo $Scope, http://plnkr.co/edit/2jz0ieeCWJE6tvzXK69A?p=preview
Please what could be the issue or could this be a bug when Controller As syntax is applied in this context, thanks

your toggleSelection function is doing a similar job to ng-model, except that ng-model has a selected property for each user in your $scope code, but a singular vm.selected property in the Controller As version, due to how JavaScript Prototype Inheritance works with primitives. This is a prime example of where not using a . in bindings causes an unexpected result.
The ng-model in this case is changing vm.selected from an array into a boolean, which is cascading to an error in your exist function, which now sees a boolean that doesn't have a .indexOf property.
In this case, your toggleSelection code is doing what you need for the rest of your code logic, and you don't actually need ng-model.

In your plunkr, you bound the vm.selected to a checkbox; this tells angular to set it to a Boolean. When you try to call .indexOf on it, it fails because checkboxes with ng-model, by default, are either true or false.
See here: https://docs.angularjs.org/api/ng/input/input%5Bcheckbox%5D

Knockout arrayForEach undefined property

I'm having trouble trying to get a number from each item in a knockout observable array and add the numbers together and assign it to another computed variable. Here's what I have right now...
Semesters: ko.observableArray([
{
semesterName: "Fall",
semesterCode: "300",
PlannedCourses: ko.observableArray([]),
totalCredits: ko.computed(function(){
var total = 0;
ko.utils.arrayForEach(this.PlannedCourses, function (course) {
total += course.MinHours();
});
return total;
}),
},
...
What I'm trying to do is, in the totalCredits variable, I'm trying to iterate through the PlannedCourses array and get the MinHours variable for each item and add them together in the total variable. Then I return it to the totalCredits item in the Semesters array. The issue I'm having is getting the PlannedCourses variable in the ko.utils.arrayForEach part. I'm getting an undefined on it and I'm not sure why. I think it's a simple syntax error but I can't see what's wrong.
The PlannedCourses observable array is a dynamic object that is getting the list of PlannedCourses properly. It's defined in the context of itself but I'm not passing it to the totalCredits computed function properly.
I hope this is clear enough. Thank you for your help!
Note: All the rest of the code is working as intended. The only part that isn't working is the totalCredits computed function. I'm not sure if anything within the ko.utils.arrayForEach is working as I haven't been able to get that far.

You're going to need to change the way you populate your Semesters observable array to use a constructor function in order to get a reference to the correct scope for this:
function semester(name, code) {
this.Name = name;
this.Code = code;
this.PlannedCourses = ko.observableArray([]);
this.totalCredits = ko.computed(function(){
var total = 0;
ko.utils.arrayForEach(this.PlannedCourses(), function (course) {
//Note the change to "this.PlannedCourses()" above to get the underlying array
total += course.MinHours();
});
return total;
}, this); //now we can pass "this" as the context for the computed
}
See how we can now pass in an object to the second argument for ko.computed to use as the context for this in the inner function. For more information, see the knockout docs: Managing 'this'.
You then create new instances of semester when populating your array:
Semesters: ko.observableArray([
new semester("Fall", "300"),
new semester(...)
]);
This approach also means you have a consistent way of creating your semester objects (the computed is only defined once for one thing), rather than possibly incorporating typos etc in any repetition you may originally have had.

As others already mentioned your this is not what you think it is. In your case the context should be passed to the computed as follows:
totalCredits: ko.computed(function() {
// Computation goes here..
}, this)
Another approach could be to store the correct this to some local variable during the object creation (ex. var self = this; and then use self instead of this).
However, ko.utils.arrayForEach doesn't work with observable arrays but works on pure JavaScript arrays, so you should unwrap the observable array to access the elements of the underlying array:
ko.utils.arrayForEach(this.PlannedCourses(), function(course) {
// ...
});
// Or
ko.utils.arrayForEach(ko.unwrap(this.PlannedCourses), function(course) {
// ...
});

The scope (this) isn't what you think it is.
See http://knockoutjs.com/documentation/computedObservables.html
try adding your context, like the following:
Semesters: ko.observableArray([
{
semesterName: "Fall",
semesterCode: "300",
PlannedCourses: ko.observableArray([]),
totalCredits: ko.computed(function(){
var total = 0;
ko.utils.arrayForEach(this.PlannedCourses, function (course) {
total += course.MinHours();
});
return total;
}, this), // new context passed in here
},
...
Doing this passes in the context of the array item itself into your computed function.
Edit:
you may need to access the Semesters object inside you loop, and add some way to reference the current item:
Semesters: ko.observableArray([
{
semesterName: "Fall",
semesterCode: "300",
PlannedCourses: ko.observableArray([]),
totalCredits: ko.computed(function(){
var total = 0;
for( var i = 0, len = Semesters().length; i < len; i++ ) {
// check current array item, possibly add an id?
if( Semesters()[i].semesterName === "Fall" &&
Semesters()[i].semesterCode === "300" ) {
ko.utils.arrayForEach(Semesters()[i].PlannedCourses, function (course) {
total += course.MinHours();
});
break; // done searching
}
}
return total;
})
},

How can I make Ember.js handlebars #each iterate over objects?

I'm trying to make the {{#each}} helper to iterate over an object, like in vanilla handlebars. Unfortunately if I use #each on an object, Ember.js version gives me this error:
Assertion failed: The value that #each loops over must be an Array. You passed [object Object]
I wrote this helper in attempt to remedy this:
Ember.Handlebars.helper('every', function (context, options) {
var oArray = [];
for (var k in context) {
oArray.push({
key : k,
value : context[k]
})
}
return Ember.Handlebars.helpers.each(oArray, options);
});
Now, when I attempt to use {{#every}}, I get the following error:
Assertion failed: registerBoundHelper-generated helpers do not support use with Handlebars blocks.
This seems like a basic feature, and I know I'm probably missing something obvious. Can anyone help?
Edit:
Here's a fiddle: http://jsfiddle.net/CbV8X/

Use {{each-in}} helper. You can use it like like {{each}} helper.
Example:
{{#each-in modelWhichIsObject as |key value|}}
`{{key}}`:`{{value}}`
{{/each-in}}
JS Bin demo.

After fiddling with it for a few hours, I came up with this hacky way:
Ember.Handlebars.registerHelper('every', function(context, options) {
var oArray = [], actualData = this.get(context);
for (var k in actualData) {
oArray.push({
key: k,
value: actualData[k]
})
}
this.set(context, oArray);
return Ember.Handlebars.helpers.each.apply(this,
Array.prototype.slice.call(arguments));
});
I don't know what repercussions this.set has, but this seems to work!
Here's a fiddle: http://jsfiddle.net/CbV8X/1/

I've been after similar functionality, and since we're sharing our hacky ways, here's my fiddle for the impatient: http://jsfiddle.net/L6axcob8/1/
This fiddle is based on the one provided by #lxe, with updates by #Kingpin2k, and then myself.
Ember: 1.9.1, Handlebars: 2.0.0, jQuery 2.1.3
Here we are adding a helper called every which can iterate over objects and arrays.
For example this model:
model: function() {
return {
properties: {
foo: 'bar',
zoo: 'zar'
}
};
}
can be iterated with the following handlebars template:
<ul class="properties">
{{#every p in properties}}
<li>{{p.key}} : {{p.value}}</li>
{{/every}}
</ul>
every helper works by creating an array from the objects keys, and then coordinating changes to Ember by way of an ArrayController. Yeah, hacky. This does however, let us add/remove properties to/from an object provided that object supports observation of the [] property.
In my use case I have an Ember.Object derived class which notifies [] when properties are added/removed. I'd recommend looking at Ember.Set for this functionality, although I see that Set been recently deprecated. As this is slightly out of this questions scope I'll leave it as an exercise for the reader. Here's a tip: setUnknownProperty
To be notified of property changes we wrap non-object values in what I've called a DataValueObserver which sets up (currently one way) bindings. These bindings provide a bridge between the values held by our internal ArrayController and the object we are observing.
When dealing with objects; we wrap those in ObjectProxy's so that we can introduce a 'key' member without the need to modify the object itself. Why yes, this does imply that you could use #every recursively. Another exercise for the reader ;-)
I'd recommend having your model be based around Ember.Object to be consistent with the rest of Ember, allowing you to manipulate your model via its get & set handlers. Alternatively, as demonstrated in the fiddle, you can use Em.Get/Em.set to access models, as long as you are consistent in doing so. If you touch your model directly (no get/set), then every won't be notified of your change.
Em.set(model.properties, 'foo', 'asdfsdf');
For completeness here's my every helper:
var DataValueObserver = Ember.Object.extend({
init: function() {
this._super();
// one way binding (for now)
Em.addObserver(this.parent, this.key, this, 'valueChanged');
},
value: function() {
return Em.get(this.parent, this.key);
}.property(),
valueChanged: function() {
this.notifyPropertyChange('value');
}
});
Handlebars.registerHelper("every", function() {
var args = [].slice.call(arguments);
var options = args.pop();
var context = (options.contexts && options.contexts[0]) || this;
Ember.assert("Must be in the form #every foo in bar ", 3 == args.length && args[1] === "in");
options.hash.keyword = args[0];
var property = args[2];
// if we're dealing with an array we can just forward onto the collection helper directly
var p = this.get(property);
if (Ember.Array.detect(p)) {
options.hash.dataSource = p;
return Ember.Handlebars.helpers.collection.call(this, Ember.Handlebars.EachView, options);
}
// create an array that we will manage with content
var array = Em.ArrayController.create();
options.hash.dataSource = array;
Ember.Handlebars.helpers.collection.call(this, Ember.Handlebars.EachView, options);
//
var update_array = function(result) {
if (!result) {
array.clear();
return;
}
// check for proxy object
var result = (result.isProxy && result.content) ? result.content : result;
var items = result;
var keys = Ember.keys(items).sort();
// iterate through sorted array, inserting & removing any mismatches
var i = 0;
for ( ; i < keys.length; ++i) {
var key = keys[i];
var value = items[key];
while (true) {
var old_obj = array.objectAt(i);
if (old_obj) {
Ember.assert("Assume that all objects in our array have a key", undefined !== old_obj.key);
var c = key.localeCompare(old_obj.key);
if (0 === c) break; // already exists
if (c < 0) {
array.removeAt(i); // remove as no longer exists
continue;
}
}
// insert
if (typeof value === 'object') {
// wrap object so we can give it a key
value = Ember.ObjectProxy.create({
content: value,
isProxy: true,
key: key
});
array.insertAt(i, value);
} else {
// wrap raw value so we can give it a key and observe when it changes
value = DataValueObserver.create({
parent: result,
key: key,
});
array.insertAt(i, value);
}
break;
}
}
// remove any trailing items
while (array.objectAt(i)) array.removeAt(i);
};
var should_display = function() {
return true;
};
// use bind helper to call update_array if the contents of property changes
var child_properties = ["[]"];
var preserve_context = true;
return Ember.Handlebars.bind.call(context, property, options, preserve_context, should_display, update_array, child_properties);
});
Inspired by:
How can I make Ember.js handlebars #each iterate over objects?
http://mozmonkey.com/2014/03/ember-getting-the-index-in-each-loops/
https://github.com/emberjs/ember.js/issues/4365
https://gist.github.com/strathmeyer/1371586
Here's that fiddle again if you missed it:
http://jsfiddle.net/L6axcob8/1/

angular: $watch set in a loop

I do the following
$scope.product.orders.forEach(function (order) {
$scope.$watch('order.details.items.length', function (n, o) {
if (n !== o) {
//do something
}
});
}, true);
where details is an object and items is an array.
The $watch is triggered once for every orders in the collection, with n and o being undefined.
Then whenever I add an item to the items array, the $watch is not triggered. Why is that ? There is no errors in the log.
note: I know that creating a $watch in a loop is clearly not a good thing performance-wise, it's a workaround for now.

If the first parameter of $scope.$watch is a string, it defines an expression that is evaluated on your scope. Usually this is a scope variable. In your case order is not a scope variable but a parameter of the forEach's handler function. You have to use the function way in this case:
$scope.product.orders.forEach(function (order) {
$scope.$watch(function () {
return order.details.items.length;
}, function (n, o) {
if (n !== o) {
//do something
}
});
}, true);

For a collection object/array, you should use $scope.$watchCollection instead.
$scope.$watchCollection('order.details.items', function (collection) {
// fires when collection changed, whenever it's length changed or item(s) changed.
})

Userscript - Replace a variable's property with a function

A website has the following code:
var Items = {
drop: function (a, b, d) {
if (!(typeof a == "undefined" || typeof sockets[a.id] == "undefined")) {
SSocket.send(sockets[a.id], {
action: "item_drop",
data: {
id: d
}
});
Inventory.add(a, d)
}
},
give_to_player: function (a, b) {
Items.drop(a, void 0, b)
},
take_from_player: function (a, b) {
var d = clients[a];
Inventory.remove(d, b);
Player.send_inventory(d.id)
},
};
I am trying to replace the give_to_player property with my own function using a userscript. However, I am having zero luck doing so. I am familiar with javascript injection and the variable scope.
I have tried the following:
Object.defineProperty(window.Item, 'give_to_player', {
value:
function(a,b){
console.log('Change occured');
}
});
This does not generate any errors, however the change does not take hold and the console remains empty. I have tried Object.defineProperties as well with no luck.
Finally the following code failed to produce results either:
window.Item.give_to_player = function(a,b){ console.log('Change occured');};
Does anyone have any suggestions?
I am using Chrome to run my userscripts.

The second method would work if you change the name to Items with a s and drop the window in the method to just Items.give_to_player = function(a,b){ console.log('Change occured');};.
EDIT: the var in var Items makes the method not accessible thru the window scope. if the var was dropped this window.Items.give_to_player won't throw error but since its there you'll not need to use the window in front of Items.(if that makes sense)
JSFIDDLE
side note: your error
window.Items.give_to_player = function(a,b){ console.log('Change occured');};
// Uncaught TypeError: Cannot set property 'give_to_player' of undefined

I really don't know how the rest of code looks like (if that object is in some particular scope, deeply nested or what) but if Items object is in global scope you can define AFTER that object (and its properties definition) again that property and that should override the previous one:
Items.give_to_player: function () {
//write your own function
}
But I'm not sure if this will work as long as I have so little information.