Prototypes - Extending An Image Object To Make A Snowflake?
Jan 1, 2011
In the spirit of the season, I wanted to make it snow on my website. So I began digging. Eventually I ended up with a script that moved an image element down the page in a snowflake-like manner. The problem with it was it was dependant on an img element for every flake - simply no poor programming when using an Object Oriented programming language.So I decided I wanted to extend (in Java-speak; most of my programming background is in Java) the in-built Image object. The new object's src variable will lead to an image of the type of flake it is. (I want to be able to have more variance in images than a simple dot.) The new object will have a function that will allow it to move.A separate,unrelated function will control when each flakes move.
I did some more research and read about prototyping on JavaScript Kit and here (http://mckoss.com/jscript/object.htm), but I still cant seem to get this to work. JS Lint says it's bug-free, but Firefox says "move()" is an invalid function. I am presuming the problem lies in my inability to fully grasp how to extend objects in JavaScript.
<html>
<head>
<script type="text/javascript">[code].....
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Jan 2, 2011
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?
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Mar 26, 2011
Link me to a good guide or tutorial for prototypes?
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Jul 21, 2006
I have been looking at Prototype.js quite a bit lately as I need to
create a very small library of similar functionality to a subset of
Prototype.js. This is for use with Ruby on Rails.
About Prototype.js Rob G wrote:
1. It modifies the protoype of some built-in objects so that
using say, for..in with an array object produces unexpected
results.
I can see that modifying the prototypes of Object or Array could break
other JavaScript libraries that depend on for..in. Prototype.js also
adds functions to the prototype of Element. How bad is that? (I notice
that in Flanagan's JavaScript 4th edition he mentions that you can
modify the prototypes of built in objects however there is no mention
of the dangers involved.)
I then thought I could use an instance of Element as the prototype of a
MyElement constructor but that option has been squashed in the past as
being not cross browser.
Assuming I shouldn't be playing with the prototypes of built-in
JavaScript objects I can see a couple options that might still be
available. Code:
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May 20, 2009
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.
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Jan 22, 2011
I have the following code:
var img = new Image();
img.myProperty = 'something';
I've tried Image.prototype.myProperty and a few other things. It seems IE just doesn't want me extending the Image object.
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Mar 18, 2004
I'm looking for a way to add more field depending on the user's input,. e.g. the user inputs ཆ' in the option, and 10 more sets of fields are displayed below on the same page. How do I go about accomplishing this?
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Sep 26, 2005
I'm embarking on a rather interesting wine cellaring project where I need to enable a user to add form fields (a complete table row with several fields) on demand.
If they start filling out the form and need another row for another bottle, I need them to be able to click a button that adds a new row to the table with the same fields.
I also need perhaps another button that will create the row and duplicate the form field values of that row. The winery, wine namen and variety may be the same but the year may change and I dont wan thte user to have to do any double entry. I've been researching DOM and have been looking at sites like Quirksmode.
Am I heading in the right direction? I'm just about to go an buy a book on DOM and start really getting into it.
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May 9, 2010
how can I make simple mouseover image tooltip on the little cubic image in the first column of every row - when it's mouseovered, the image of current book, which is in that row, should be in tooltip.The name of every the image in folder "slike" is exactly the same name as the value of "slike" in xml for every book(knjiga)!
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Nov 22, 2011
I was wanting to know how to properly make an image change when you hover over the main image.URL...And I want ALL the images to change as soon as you hover over each image.Now here's the problem. Whenever I layout my coding like that, when I hover over ANY image, an image I don't want to change, changes.So is there any way that I can get ALL images to work without having to create external JavaScript files?
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May 11, 2010
Using a UI dialog I'd like to load in 10 or so images. Each would be unique and after you click on one the following needs to happen:
1. Image appears on the parent page in a specified ID.
2. A "hidden" field is updated so that when the user submits the db is updated with their selection.
3. Dialog closes automatically.
That's it. Basically it would work similar to "datepicker".I'm using the latest 1.4 and ui and been making great progress as learning basics. I need to do the above and it seems like such a no brainier and or it should already exist but after 2 days of searching and trial and error...
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Jul 23, 2005
Javascript has a very small math function list. However there is no
reason that this list can not be extended greatly. Speed is not an
issue, unless you nest complicated calculations several levels deep. In
that case you need much more ram than a PC has to store functions
calculated in loops so that you do not have to recalculate every time
you cycle through the nest of loops. Using a HD for storage to extend
ram is much too slow for many applications.
Some functions such as hyperbolic ones are easy to add, since they are
just simple combinations of the built in javascript math functions. I
have found a few examples on the web such as Bessel functions. I found
far fewer javascript math functions than I expected on Google searches.
Thus I have had to write several functions of my own.
See http://www.cwdjr.net/math/I0L0andI1L1.html for an example of two
"functions from hell" that are very difficult to evaluate. Fortunately
there are Fortran programs that can be used as a starting point. I was
able to modify the Fortran programs to work on javascript. I have used
these functions for technical applications in the past.
The page is set up to reject the NN 4 series, because it will not
support some of the script needed such as .toExponential(n) and
to.Fixed(n)for writing output in exponential or fixed format. I was
amazed that even the old MSNTV(former WebTV) set-top box, that no
longer is being made, will even support these output formats. I wonder
about IE4. If it will not support these output formats, I can easly
block it by checking for document.getElementById.
The code works properly on the latest versions of IE6, MSN9, Firefox,
Mozilla, Netscape, and Opera. I am not selling anything, so for a
special interest page such as this, I see no need to support older
browsers.
The advantage of doing math with javascript is that it is so portable.
You can do it anywhere you can use a computer, or you can do it on your
own local computer offline. There are several math programs for PCs
that will do very much more than you can hope to do with javascript.
Unfortunately the program I would like costs about US$ 1800. Also there
are versions you can install on a server, but these also are expensive.
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Feb 1, 2007
I am trying to create an HTML form in which user will enter different items (he wants to purchase) in text fields. One text field is used for one item. Now it is not known in advance how much items the user will purchase so we cannot decide the total text fields required in advance. Is is possible to increase the number of text fields (using JavaScript) one by one if the user requires more fields
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Jan 9, 2007
How do I extend both the table and the input form? Ultimately, I want it to look like this:
_____________________________
|header |header |header |header |
| INPUT | INPUT | INPUT | INPUT |
Add Row of Inputs Link
_____________________________
|header |header |header |header |
| INPUT | INPUT | INPUT | INPUT |
| INPUT | INPUT | INPUT | INPUT |
Add Row of Inputs Link
I know how to make the html row by using getElementById() or so and I know how to make an input field by createElement() but how do I create and append(?) them together, specifically the multiple input fields inside of the html row?
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Nov 24, 2007
My website has demo music tracks and a Flash player. I've put the site in a frameset so that music continues to play while the user is browsing around.
The Flash player and menu are in a thin horizontal bar along the top of the page (top frame). I just realised that my nice JS drop-down menus are not displaying because of the frame... is there any way of getting them to extend beyond the frame they're contained in ?? Code:
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Aug 5, 2010
I want to make an moving image. In time it should change to other image with other button. Also it could be changed by user. The change should be dynamic like moving from left to right.
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Oct 7, 2011
I am using prototypes (library) ajax methods and one of them is properties. I am passing in the name value pairs:
var itemFilter = "MajorCat: Shoes",
parameters: { q : qry ,fq: itemFilter },
But when I request, it gives me this in the url: MajorCat%3AShoes That won't work, the search application on the backend doesn't filter properly because of the "%3A" instead of ":". When I manually pass in via the url: MajorCat: Shoes (at the end of the query) it works. So, that ":" is getting encoded. How do I get that IN the hash and make sure the request is unencoded when it goes out?
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Jul 14, 2009
I have this class, (just the signature)
javascript Code:
var parent_child = function(po, ps, co, cs){
var url = 'http://xyz.com/abc/';
var pars = [], childs = {}, tmp;
this.p_added = function(urlFrag){
[Code]....
What i want to do is to create a new class with the above one as the super class, pass in one more variable to the constructor and override the p_added function. I thought of doing something like xpc = new parent_child(); and override the function with xpc.prototype.p_added = function(){}
how to pass in another variable to the constructor and make it private to the new class.
I believe there is a nice and concise way to achieve what i want to, but i can't find it. And the fact that OOP in javascript can be implemented in several different ways doesn't help my cause.
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Jul 11, 2011
I am making a small gallery script. When a user clicks an image, I would like for a function to be called that tells the browser where that image is located in an object. For example:
[Code]...
It works, I just don't like it because it is messy and it seems sensible that some workaround exists.
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May 17, 2010
A client is using an analytics tracking script that needs to be updated each time the DOM is modified (ie, an element is added or removed). Basically this script allows the client to track user actions on the site (clicks, mouseovers, etc.) and, if the user is having issues, replay the entire session to help them with their problem. The issue we're running into is that this tracking script takes a cache of the DOM tree on page load, and when the DOM is updated it needs to specifically be notified that there has been a change... or else the script won't be able to see the nodes that have been added/removed.
Assuming all DOM manipulation is done using jQuery functions, is there a way to run some function every time the DOM is manipulated? I've noticed that all the DOM manipulation functions seem to run through the internal $.fn.domManip function, so I was wondering if it's possible to extend or replace this function from another JS file (assuming of course that all the manipulation functions DO in fact run through $.fn.domManip)?
Example (don't take this code seriously, it's more meant to illustrate what I'm trying to do):
var oldDomManip = $.fn.domManip; //Copy the function (I know this isn't right)
$.fn.domManip = function() {
oldDomManip(arguments);
//update the analytics program by calling it's update function here...
}
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Sep 26, 2009
I'm writing a plugin for jQuery for catching 2 succesive keypresses. I'll paste the plugin I wrote below It doesn't work on Opera . The Developer tools of Opera gave no errors and I can't find any problems, it just doesn't work.(I've used Opera 10.0). o it only works on Firefox (tested on 3.0.14). I'm curious if there is a way to find out why it's not working on Opera and to fix it.
[Code]...
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Nov 24, 2009
I was wondering if there are any sites dedicated to ending javascript objects using the prototype property to give them features like trimming string, removing elements of arrays by name, removing duplicates in arrays, etc. Granted I have functions to do this but there's probably a ton of other good ones out there. Most things I've seen are frameworks like JQuery (which is awesome) but it doesn't extend these objects.
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Mar 8, 2010
I am preloading some images, so prior to the downloading I have:
In Mozilla: initially WxH = 0x0 ... after img downloaded WxH = good# x good# the div just stretches just the right amount to fit snuggly around the newly loaded image;
But the other browsers do different things;
My current solution, which works, uses a new Image().width approach where I manually resize the container div;
How to get the other browsers to automatically resize the container divs;
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Mar 30, 2011
Consider the following:
Code:
myObjLit = {
prop1:null,
[code]....
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Jun 10, 2009
I have a LARGE, hi-resolution image that I am trying to use as the background for a page. Because it is so large, it takes a while to download. Because of this, I wanted to load the image behind-the-scenes and show it once it is downloaded.
To accomplish this, I'm using the following JQuery code:
This code clearly downloads an image and appends it to my DIV element. However, I really want to set this downloaded image to the background-image CSS property of my DIV. The reason why is because I have content inside the DIV that should serve as the foreground.
How do I dynamically download an image, fade it in, and use it as a background?
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Oct 21, 2010
I am working wiht this JQuery plug in that now one of my clients wants to turn it into a slideshow feature. I am not that familiar with JQuery plug ins so I wanted to get some input from some of you.
On the header of my html page:
Code:
$(document).bgStretcher({
images: ['1.jpg', '2.jpg', '3.jpg', '4.jpg'],
imageWidth: 1668, imageHeight: 1035, nextSlideDelay: 3000, slideShowSpeed: 4000
});
I was able to add a click handler to trigger the a function on the plugin called loadslide().
Code:
$(document).ready(function ($) {
$('.slideNo').each(function (i) {
$(this).click(function () {
loadSlide(i);
[Code].....
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