In JavaScript 1.5, objects can use special getter and setter functions
[1] for properties. However, these only seem to be implemented in Gecko
and, AFAICT, don't seem to be part of ECMAScript.
Is there an alternative syntax I can use that is standardised in
ECMAScript and also (preferably) interoperably implemented in several
browsers? Or, do I have to use ordinary getFoo() and setFoo() functions. Code:
I find the JavaScript's Object.prototype and getter/setter mechanism
very nice. However, I need some help with extending an object with
getters/setters in the derived class. For example:
A : function () {}
A.prototype =
{
a : null,
get a : function () { return a++; }
};
B : function () {}
B.prototype = new A;
Now, I would like to define a getter/setter in B. How do I do that?
There is no way to use the same syntax as in "A.prototype = ..." above.
how to add extra properties to html elements as I was storing data in html attributes. After looking at some others code including Raphael and this addEvent code. [URL] They seem to treat objects just like an array. obj[property] = value; This would have been extremely helpful to know previously as I have needed to be able to include variables in property names - but have resorted to making the whole thing a string and calling exec() on it.
View 2 Replies View RelatedI created a method for displaying an object's properties:
As long as renderfunction = false, the object is fine coming out of this function.
However, if I change renderfunction to true, all my properties become undefined. Why isn't this working as I expect it to?
I'm trying to get the properties for the following objects:
0: [object Object]
1: [object Object]
2: [object Object]
3: [object Object]
This was generated by using the following code:
[Code]...
Since object names can't simply be a number ie(this.oProducts.Product.0), how can I access the object properties in the list above?
I have the following question.
In my code, Ifirstdeclare a GLOBAL property to store all my global var's in, (with already some properties)[code]...
Does the second block of code overrides the first GLOBAL object? Is there a way to push more properties to an existing object using the same pattern?
i'd like to know objects properties and/or methods.
saying i do have an object "o" being part of the dom (a div or an ul...)
how could i list (introspection) all the properties and methods attached
to this object ?
i know it is possible in javascript but don't remeber how to ...
Do many programmers remember most of the object properties and methods or do they use IDE or references to find those specific objects. I'm starting to learn Javascript and seeing all the different type of objects available can be depressing. :(
View 2 Replies View RelatedI am fairly familiar with the concept of Objects and their properties and methods, but javascript being object based as opposed to object oriented has me stumped on how to access an object's properties from an onclick event handler created for another object created within the original object.
In the example below, I have a constructor function called anyObj. to which I pass an object reference to an element.
anyObj has 3 properties and one function increaseWidth()
increaseWidth() creates a new button with an onclick event handler and this is where I have a problem.
The onclick function needs to increase the value of anyObj's this.width property. I originally had a line this.width += 10; in the onclick but quickly realised why this wasn't working because the this in the onclick function refers to the new button object and not the this.width property of anyObj.
The workaround I have used, and it works, is to make a copy of all the this.xxxxx properties. eg. width = this.width; and use the width variable in the onclick as you can see below. This "workaround" works fine but doesn't feel ideal to me.
So is there a better way to access the anyObj()'s properties from within the onclick function than the way I have done it? Obviously I would prefer to not have to make copies of all the anyObj() properties like I have to make them accessible to the onclick function.
function anyObj(divObj){
this.elem = divObj;
this.width = 50;
this.height = 50;
[Code]....
Say x in a XML Http Request Object ... meaning it's either XMLHttpRequest (firefox) or ActiveXObject (IE)
This line of code works in firefox...
x.someProp = "someValue";
alert(x.someProp);
But in IE I get "Object doesn't support this property or method" I need to place a custom property on the object. Is there any way I can do that in IE?
I've already tried ActiveXObject.prototype.someProp = "";
I've created an object and within this object, I've added an eventlistener. But the problem now is that after addEventListener is being called to access a callback function, the callback function is not able to access the properties within its own class. Code:
View 14 Replies View RelatedI am fairly familiar with the concept of Objects and their properties and methods, but javascript being object based as opposed to object oriented has me stumped on how to access an object's properties from an onclick event handler created for another object created within the original object.In the example below, I have a constructor function called anyObj. to which I pass an object reference to an element.
anyObj has 3 properties and one function increaseWidth()
increaseWidth() creates a new button with an onclick event handler and this is where I have a problem.The onclick function needs to increase the value of anyObj's this.width property. I originally had a line this.width += 10; in the onclick but quickly realised why this wasn't working because the this in the onclick function refers to the new button object and not the this.width property of anyObj.
The workaround I have used, and it works, is to make a copy of all the this.xxxxx properties. eg. width = this.width; and use the width variable in the onclick as you can see below. This "workaround" works fine but doesn't feel ideal to me.So, what I am asking advice on is, is there a better way to access the anyObj()'s properties from within the onclick function than the way I have done it? Obviously I would prefer to not have to make copies of all the anyObj() properties like I have to make them accessible to the onclick function.
Code:
function anyObj(divObj){
this.elem = divObj;
this.width = 50;
[code]....
I have the empty object and two variables:
[Code]...
Code JavaScript:
function dropdown() {
}; dropdown.prototype = {
sele: $('.select'),
city: [],
scope: [],
type: [],
init: function(json) {
if(json.location.length) {
for(var i=0; i<json.location.length; i++) {
this.city[i] = json.location[i].city; .....
this.scope[i] = json.location[i].scope;
}}.....
getUrl: function() {
return location.pathname+location.search;
},
setUrl: function(paramType, param) {
return this.QueryString(paramType) ? this.setQueryString(paramType, param) : this.getUrl()+"&"+paramType+"="+param;
}};
Well, I've been working with JS for three years and have a great experience here. But! I still have no really acceptable answer to the following
question:
What is the principle difference between declaring methods/properties
in the constructor function body and via prototypes.
Are there any real GURUs? Let's discuss the issue.
I want to programmatically list all properties of JS object from C++ code (I am using Mozilla's JSAPI). I know I can go up the prototype chain with JS_GetPrototype, then enumerate each object's own properties with JS_Enumerate.
View 7 Replies View RelatedI have an object: Myobject and properties for the object: Myobject.color, Myobject.width, Myobject.height The scripts returns TRUE if I query Myobject.color or Myobject.width etc. I want to loop through de properties like so:
Code:
var properties = ['color', 'width', 'height']
for (var i=0; i<properties.length; i++) {
Myobject.properties[i]; // Returns UNDEFINED
}
How to make it works? (Should returns TRUE)
I've got an image gallery in which users can navigate between the next and previous image by clicking on the right or left half respectively of the current image. When the mouse is over the left half an arrow pointing to the left is shown on the image and when on the right an arrow to the right. It works fine if i use inline javascript but i'm trying to achieve the same effect unobtrusively and with an addEvent function. The onmouseover part works fine but from the function that fires on the onmouseout event i get the following error in Firefox and the arrow is not hidden:
View 2 Replies View RelatedI don't know why but after the animate() function it's like all the properties get wiped.
PHP Code:
bubble.prototype.expand = function() {
var _this = this;
this.mLeft = parseInt($(this.div).css('margin-left').split('px')[0]);
this.mTop = parseInt($(this.div).css('margin-top').split('px')[0]);
this.iWidth = $(this.iconImg).width();//icons dimensions
this.iHeight = $(this.iconImg).height(); .....
Subject line would seem to say it all:
How does one trigger the execution of a method within an object or any
other code/function with the setting of an object property?
More elaboration for those who want it:
Suppose we have anObjectType, with a property .description, whose value
can be a string, and the value of .description actually describes the
structure of anObjectType as a string. (The details are not important
about how the structure is described, but if you want something concrete,
think of 'anObjectType' as a DOM Node of type NODE_ELEMENT, and
..description as the property .innerHTML.)
When an instance of anObjectType is created, the value of description is
created with the instance. Indeed, the value of description may not be
set with the construction of anObjectType, but it might be added to the
prototype of anObjectType.
But the property .description is not merely read-only. Fetching the value
of .description returns the string which describes the structure of the
object in a meaningful way.
When .description is set with a value of type string, the string is
checked to see if it properly describes a legally formed structured for
anObjectType, and the instance (and only that instance) of anObjectType is
completely re-built: it might possibly be destructed and then re-
constructed, or all properties (but not methods) which involve descendant
objects are changed to conform to the described structure.
The question is, the setting of a string value of the property
..description of object anObjectType does not automatically trigger a
method/methods (or an exception??) for doing something (such as
restructing the object) as a result of the setting of an object property.
This object was passed to my click event handler. Why are so many properties missing? The click event came from an <a> in a <li>, propagated down to the <ul> on which the handler was set.
If I click on the <ul>, the event object looks "normal".
[Code]...
if I'm using IE only I can get around just fine, but I haven't really had a lot of experience sniffing out other browsers and trying to create different code branches to create the same effect on a particular browser.
In this case I've got a series of layers that correspond to some links. When someone mouses over the link, the layer becomes visible. When someone mouses out, I want the layer to fade out. Code:
I've got a javascript object is "is" that has dynamically populated properties. I make an ajax call to my database to grab usernames associated with unique ID's and populate the javascript. I can call a property directly like this: aler (is.softUser1) or alert(is.softUser2) and show the corresponding values. However since what is being returned from the database is dynamic I may need to call is.softUser5 or is.softUser8 so I need to do that call dynamically. code...
and that obviously doesn't work.
Is there a way that I can dynamically call that property based on whatever value "user" is?
I have an object on the document element that allows for other components to register with it, i have a custom event something along$(document).bind("register",function(thechild)..So in the child object when they are created i call$(document).trigger("register",this);And indeed i get the DOM object. However i'm looking for the plug in object, i want to be able to call methods on the passed childobject and access it's Config.Does that make sense? How can i write a plug in that is applied to various objects that also registers itself with an 'overseer' object on the document element in such a way that i can allow that overseer object to call methods on any registered child objects?
View 2 Replies View RelatedI was under the impression, via W3Schools that 'checked' is only a property of radio/checkbox input objects. I was trying out this code that loops through several different types of inputs:
Code:
//start loop
var elem = theInput[i]; //grab the input
if('checked' in elem && !elem.checked) { continue; }
//...do some other stuff
//end loop
As you can tell, I want to skip all radio/checkbox inputs that aren't checked because they are meaningless in my circumstance.....the problem is, it skips over EVERYTHING (that isn't checked) regardless of if it's a hidden input, text input, password input, etc..... I did a quick test:
[Code]...
Does the "semicolon insertion" really affect you if you format code as
function x (y)
{
// ...
}
instead of:
function x (y) {
// ...
}
The jslint page complains about lines ending in ) due to the nebulous
idea of "semicolon insertion". I have not reviewed the ECMAScript pdf
in great detail to try to pin this pretty-printing issue down. In
general, I find that code formatted in the "K&R" style (opening brace
on same line as if, while, function) confusing and difficult to read
compared with placing curly braces on separate lines.
On another subject, the difference between inner functions defined
explicitly versus defined using function expressions seems like a good
one for a FAQ. Under what circumstances does it make a real
difference whether you use function expression versus function
statement versus Function object?