I had read from books that the constructor property of object is inherited from its prototype. And the prototype can be changed dynamically. New property can be added to or deleted from object even it was created before the prototype change.
But I got confused on below codes.
But the actual result (both IE and firefox) is
What happens if you do this?
function Person() {}
Person.prototype = 7;
var ted = new Person();
Also what happens if you set Person.prototype to an array or function?
How would I go about copying all the prototype functions AND the constructor from one object into another object, and then call them?
I know I can use this.example.call(this), but that's not an acceptable solution. I want to deploy this style over dozens, potentially hundreds of objects.
I have a requirement to override the constructor of a javascript class. I have to execute the current constructor code and then call a javascript method. Basically, I need to execute a javascript method whenever an object of that particular class is created in addition to whatever is being done now. I do not want to copy and paste the current constructor code and override the initcomponent method. I am looking for an alternative for that.
View 5 Replies View RelatedI would like to change the alt-text with the changing of the image during a
mouseover action.
Can document.images[0].altView be changed dynamically?
I have static object and I want remake it to a constructor with property 'length' which would be not enumerable in for loop... This is my object and how I generate it
[Code]...
I've ammended my code now so that I'm using objects, constructors and prototypes.
If I use the standard constructor.prototype.functionname = (){......} type of setup it works okay.
However I'm now experimenting with overwriting the prototype with a literal. As in the code below. i.e. constructor.prototype = {functionname : function() .......
Doing it this way my first new object instance fails. The subsequent new objects are fine.
I ran a check on the properties of the 1st object with '!hasOwnProperty and name in' and the result is that the prototype (or pointer to a prototype) is missing.
So the first new object of FontTrans (oH) has
Code:
1 property is Heading
.
.
9 property is Delay
[Code].....
I have the following situation:In CSS:
[Code]...
How can I get the CSS properties from such "class inheritance" set-up? More in particular, how can I get the marginLeft from the class "combination" .northSouth.ambiPixelBox? I tried the following in jQuery, but that failed:
[Code]...
what's the point of using x.constructor.prototype? (highlighted in red) why not directly use x.prototype. classname to check whether 'classname' property is in this class?
View 14 Replies View RelatedI 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?
View 8 Replies View RelatedI'm not sure why this: Code: console.log(instance2.getAnotherKey()()); returns Object { a = "a" } when I clearly reassigned the value of the a property. Reassigning the property caused change in this line:
Code:
ref.a = 'abc'; console.log(inst.getZ()); //Object {a="abc"} So why does it work when you call an instance method in the constructor (e.g. this.getZ()) but doesn't work when you call the instance method in prototype?
[Code]...
I get an error when I try to dynamically add an attribute to some elements, since I been getting the error "Object doesn't support this property or method" in IE I reduced the attribute value to just alert.
Code JavaScript:
Note that in firefox all the elements with the class boxcontainer gets "hello world" alert. I removed this specific code (shown above) out of the page and the error in IE goes away, so I'm 100% sure nothing else is causing it.
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
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?
So I have a table. With jquery I change border properties of several td. If later on in the code those same td have their background color changed by jquery, their borders return back.
Even if nothing is changed, nevertheless after some time some of the borders would seemingly randomly suddenly show up. I am working on a maze so this really spoils the game.
Code:
if($("crush",xml).text()=='1'){
border1=$("border1",xml).text();
border2=$("border2",xml).text();
[Code].....
I need to detect the "name" of the constructor of an object. For example, myArray.constructor === Array is true, but I want something where that === 'Array' is true. I've heard of Object.constructor.name, but it's not widely compatible. (preferably without involving regular expressions)?
View 4 Replies View RelatedI am trying to understand why I had an error, or why my solution worked. In my HTML I had:
<script language="JavaScript" type="text/javascript" src="Book.js"></script>
<script language="JavaScript" type="text/javascript" src="Book_TEST.js"></script>
Book.js said:
[Code]....
Now, the code worked fine in both script. (i.e., no more error.) So far as I can tell, the only differences between the first and next version of Book.js are the comments and the whitespace. Am I missing something? Can the comments or whitespace somehow effect the logic with which this code has been executing? If I get an error like this again, is there an easier/better way to fix it than to essentially retype the code?
How to extend the constructor for the date object of the javasccript so that whenever a call is made to the constructor, I want to perform a particular action? Basically how to define wrappers for default javascript methods or objects like Date() so that I can perform some action and then invoke the original method? So basically if I have something like var a = new Date(); I want it to (say) alert the value of the date everything Date() is called and then execute the default date constructor.
View 3 Replies View RelatedI need to create a constructor for a computer object. This object must have three properties: speed, and mem_live mem_dead. Then I need to create a new object using this constructor and then have its properties displayed on the screen.Look at what I'm up to so far:
function Computer(speed, mem_live, mem_dead)
{
this.speed = speed;
[code]....
It always just shows : 4.0ghz, true, false
function show() {
var s = '' ;
for (var i = 0; i<arguments.length; s += '
'+arguments[i++]) ;
typeof(window) != 'undefined' ? window.alert(s) : WScript.Echo(s) ;
}
function f(){}
show('delete(f):',delete(f)) ; // false
g = function(){} ;
h = new g() ;
show('h:',h) ; // [object Object]
show('delete(g):',delete(g)) ; // true
show('h.constructor:',h.constructor) ; // function(){}
show('delete(h.constructor):',delete(h.constructor )) ; // true
show('h.constructor:',h.constructor) ; // function(){}
is there a delete for a object inside the constructor, while i init it?
i will try something like that:
var obj = function(a)
{
if (!a) delete this;
this.a = a;
}
Sorry, bad title. Anyway, is there a way to pass the arguments to an object
instantiated via a constructor using the arguments object and have it
expanded, so to speak, so that it doesn't appear as a single argument? I'm
sorry, this explanation is just atrocious, but I can't think of exactly how
to word it. Maybe an example...
Take for instance Function.apply. It takes 1-2 arguments, the first being
the object to use as the context, and the second being either an array or an
instance of the arguments object which are to be the arguments for the
function. I want to do something similar but I want to also basically use
the new operator so that I get back an object.
Here's a snippet of some of my code, maybe this will help:
I'm sure this question has been asked many times before, but I can't seem to get the correct terms to find the answer in Google.I understand basic JavaScript inheritance. However, everything I've read makes the inheritance work something like this:
Code JavaScript:
var ChildClass = new Function();
ChildClass.prototype = new ParentClass();
ChildClass.constructor = ChildClass;
That's fine, but what happens when ParentClass's constructor needs parameters?As an example, look at the following code:
Code JavaScript:
function Furniture(color){
this.color = color;[code)....
How could I "copy" Furniture's constructor into the Chair object? Better yet, how could I copy Furniture's constructor and then add some functionality to it?
I have a code set up something like this:
[Code]....
The problem is I keep getting an error along the lines of: TypeError: Result of expression 'house' [[object Object]] is not a constructor. It seemed to work when I wasn't passing the other objects as parameters in the constructor. I just created and assigned them later. As in:
[Code]...
I'd like to make a Degree object that inherits from the Number object and uses the Number constructor but adds a .rad() method that returns the value in radians.
If I do something like:
It generally works but I don't get Number's methods like toString and toPrecision.
I have an object with a single Method to load content from a xml file. The problem is... how do I add a property to the object to store the data loaded?? I tryed adding a simple Array inside the object, but didn't work.
[Code]...
