Adding Methods With Prototype?
Mar 19, 2010
I pulled out an old javascript object I created a while back a few days ago and I've been developing in Firefox ever since. Then I decided to test how it worked in other browsers and.....it works in none of them! Not chrome, not IE(7/8), not opera, and not safari.
It's built like this:
Code:
function myCalendar() {
//constructor function
}
myDiv.prototype.newMethod = function() {
[Code].....
It's really as simple as that....what's on the go? Do any JS experts out there know anything about this?
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Mar 29, 2010
I have a class constructor, and after the constructor a prototype method associated with that class. I'm trying to call that method from within the class constructor, but it causes an error, indicating that the method is not a property of the class.Is it not possible to access prototype methods from within the constructor? If it IS possible, how do I do it?
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Sep 20, 2005
What I am trying to achieve is an 'inherits' method similar to Douglas
Crockford's (http://www.crockford.com/javascript/inheritance.html) but
that can enable access to the superclass' priviledged methods also. Do
you know if this is possible ?
In the following example, I create an ObjectA (variable a), an ObjectB
which inherits ObjectA (variable b) and an ObjectC which inherits
ObjectA (variable c1). The 'toString ()' method of ObjectC refers to
the 'toString ()' method of ObjectA. This is possible because the
'Object.inherits ( superClass )' method adds a reference to the
superClass of an object in the object's prototype.
If I understood things correctly, the prototype is the same for all
objects of class ObjectC. Therefore, I should be able to only add the
reference to the superClass once. That is the purpose of the
'Object.initializedPrototypes' array : it keeps track of the objects
for which a reference to the superClass has been added to the
prototype.
However, when I create another instance of ObjectC (variable c2), its
prototype doesn't contain any reference to the superClass.
A workaround for this problem consists in adding a reference to the
superClass for each instance of the inferiting object (either by
bypassing the check to Object.initializedPrototypes or by adding the
reference to a priviledged member such as 'this.superClass' instead of
'this.prototype.superClass'). However, in terms of memory usage or of
"programming elegance", this seams to defeat the whole purpose of using
prototypes.
Here is the code, if any of you have got ideas...
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Nov 24, 2011
I've previously written an image carousel with lightbox and to be honest forgot about it for quite a long time. I've just been tasked with making a few modifications (I wrote this code about 6 months ago)
Now, the problem I have is that I now need to call the internal method from the ligthbox plugin.
I've tried setting a reference to this like this but it just won't play ball. I can see that the ajax feed gets called but unfortunately I can't then access it.
[Code]...
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Apr 26, 2010
I have a vvery simple javascript for a navigation menu that displays one tree. I am trying to make it so that there is a delay on the mouseout.
Code:
var DropDownMenu = Class.create();
DropDownMenu.prototype = {
[code].....
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Jul 12, 2009
I'm trying to learn more about creating and using JavaScript objects and ran into this situation the other day:
Code:
function someObject() {
var size = "large";
[code]....
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Aug 30, 2010
I need to know how to add an event to a button. The specific issue is that I want to add an event which is a prototype function of a class. Consider the following as an example:
MyTestClass = function() {
this.firstName = "Pete";
this.lastName = "Johnson";
[code]....
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Nov 25, 2011
According to ECMAScript, the root of the prototype chain is Object.Prototype. Each object has an internal property [[Prototype]] that could be another object or NULL.... However, it also says that every function has the Function prototype object: Function.Prototype, it confused me, because a function is an object, for a function object, what is its function prototype and object prototype..For example:
var x = function (n) {return n+1;};
what is the relationships of x, Object.Prototype and Function.Prototype
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Dec 14, 2009
I am trying to get to the bottom of javascript object, prototypes etc. I have a fairly good grasp of it, but I get confused the closer I get to the base object.prototype. FIrst of all, I was under the impression that all objects descend directly from Object. But some objects (like Array) seem to inherit properties and methods from the function.prototype. So does this mean that the chain is like this:
object -- function -- array Second, I noticed (on the mozilla javascript reference site that object.prototype inherits properties and methods from function.prototype and vice versa!? How can this be? I must be missing something important about understanding the chain?
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Jul 23, 2005
Can Java classes/objects be used from within the javascript code on the
HTML page? I.e., can I call a Java method from the javascript function?
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Sep 8, 2005
I have a javascript function that needs to access methods of a java
object(localTag). In my JSP I'm trying to include hidden fields for
the Strings returned from the getter method calls of the object like
so:
<html:hidden name="FrmCustomerHolding" property='<%=
"localTag.getTagName()" %>' />
<html:hidden name="FrmCustomerHolding" property='<%=
"localTag.getTagValue()" %>' />
If I can do something like this, what is the correct syntax and how do
I access this property in my javascript? When I have a hidden field
that is just a String, I access it in the javascript like
"document.getElementById("theString").value" and it works fine, but I
can't seem to find how to access the String value of a method call.
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Mar 12, 2007
I am wondering if it is possible to get the response from a method
within a given page, and that function alone? Traditionally, I have
been getting the response from the Page_Load method of the targeted
page, but now I want the response from a particular method on the
target page:
Public Sub SomeCallback(ByVal sender As Object, ByVal e As EventArgs)
'RETURN XML FOR CALLBACK
End Sub
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Jul 20, 2005
When you use addEventListener (or addEvent in IE) to call an object
method, does it call it with the correct this parameter?
The ECMAScript reference has a lot to say about the caller using
Function.prototype.call or Function.prototype.apply and passing the
correct this pointer for the context, but how does addEventListener
determine the correct this pointer. Or does it just punt and pass the
global context, thus making it impossible to refer to the object this
in an object method used as an event listener?
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Jan 31, 2010
About when to use setter methods. For example, I have this code
Should this be used like this:
I think a better question is when to use the .each loop? Since, the first line of code I have works fine.
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Mar 26, 2009
So I have this homework assignment where I need to get my application from switches to using methods to give me the same result. I usually am good in this class, but right now I am completely lost. Here is a piece of the code using switches:
/* Get Type of Math problem from the user */
input = JOptionPane.showInputDialog(null,"Enter the type of Math Problem"
+ "you would like to solve:
"
+ "Addition = 1
"
+ "Subtraction = 2
"
+ "Multiplication = 3
"
+ "Division = 4
"
+ "Enter the number of your choice: "); .....
I need to get this same result by using methods. I can use these method signatures:
public static int readProblemType(){}
public static int getAddProblem(int randomValue1 int randomValue2){}
public static int getSubProblem(int randomValue1 int randomValue2){}
public static int getMultProblem(int randomValue1 int randomValue2){}
public static int getDivProblem(int randomValue1 int randomValue2){}
public static int readAnswer(){}
Looking at what I need to do, how would I use public static int readProblemType(){} method to read the problem type? Or where should I start?
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Apr 10, 2007
Programming assignment: Write a program for analyzing El Paso weather. This program must allow the user to enter dates followed by temperatures at these dates. Assume that we are only tracing one year, so the overall number of such dates does not exceed 366. Your must then output the following information:
*the average temperature;
*the list of all the days when the temperature was below freezing (i.e., below 32);
*the hottest temperature, and the list of all the days when the temperature was the hottest.
Main difference: In the previous assignment, following our advise, you stored the dates in one array (array of strings), and temperatures in another array (array of numbers).
For this new assignment, define a class Record whose objects contain two fields:
*a field date that contains the date, and
*a field temperature that contains the temperature.
Instead of using two arrays, use a single array of records (i.e., of objects of type Record).
The problem I'm having, is that I do not know how to read from two files and store the information into one array. (For example: with this assignemnt, I need to have one array with 366 fields, and in each field there needs to be a date and temperature.)
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Jun 10, 2011
I have more of a programme design related question here: I have an object with 2 methods, those two methods are supposed to be called repeatedly one after the other (e.g. by setInterval())
window.setInterval(function() {
obj.method1();
obj.method2();
}, 100);
the problem with this code is that the execution time of those methods may increase depending on the processed data (an array with several hundred elements or more) so it may be, that the execution time of both methods exceeds the given repetition time. I could solve that by placing a call to the next function in each method, but I wonder if that is good design or not (tight coupling)
code for method2() is analogue
Obj.prototype.method1 = function ()
{
/* working code here */
[Code]....
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Aug 2, 2011
How are methods masquerading as properties? Does this make methods more flexible as objects or plain functions?
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Dec 8, 2011
When a custom object is created in javascript, then methods need to be defined for this object. Still every object has toString() method available to them, even if it is not defined. How is this method available to all the objects ? Is it inherited from some root object ?
Is sort() method available to all the objects ? What are the other methiods available to all objects ? Where can I get list of available methods ?
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Mar 1, 2009
Creating methods that can be used by all elements?
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Jul 23, 2005
I am a little confused how the memory for objects is allocated in
JavaScript. David Flanagan, in "javascript: The Definitive Guide,"
states that each property of a class takes up memory space when
instantiated. So space is created for aMethod three times in this
example: Code:
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Dec 6, 2006
I just wanted to know if there was any way to use script to display a
list of methods linked to a particular object? The object I have in
mind is getBrowser(), and I can't seem to find any documentation online
with regards to it's methods.
Also, as I am learning, it would be nice to be able to know what
methods are available for a particular object/function, without
necessarily having to spend a while looking up an object's method when
it's documented in a lot of different places, but only vaguely.
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Jan 21, 2010
I have been trying to discover why the first() and last() methods are not working in my jQuery 1.2 nor 1.3 tests. After searching for a while, I found the alternative way with filter() and eq(), but I still wonder why none of those methods work.
The API documentation [URL]... states that they are available since 1.2, but they won't work, I always get a "not a function" error. I also found a tracker entry [URL].. discussing the need for them, but nothing is clear from it.
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May 18, 2011
Let's say I have a Javascript object that looks like this:
{
events: {
"comments:added": this.add,
"comments:removed": this.remove,
"comments:fetched": this.addAll
}
}
I'd like to add this method to it, either manually, using $.extends() or _.extends():
[Code]...
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Dec 1, 2010
HTML5 brings two new methods to the js selector API: querySelector() and querySelectorAll(). These methods can be used to match elements against a group of selectors. I think, a lot of the functionality overlaps with jQuery selectors. My guess is that these new methods will be a few times faster than jQuery selectors because they are natively implemented. My question is, how will jQuery use these additions to the js selector API? Will jQuery selectors just encapsulate these new methods? If so, is this work in progress or..
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Jan 17, 2011
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. :(
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