Preserved Topic: dynamic object creation? (Page 1 of 1)

hello peeples,
ive got a nifty littel javascript, and i want to create several instances of this object, where i would have:
block1 = new block('blockid')
right... but the thing is i want it to be done as the page generates:
like
i=1

eval('block' + i) = new block('block' + i)
i++
eval('block' + i) = new block('block' + i)
you get me?
what i want to know, is - is the eval() part right?? or is it something else?
if someone can enlighten me, that would be great.
<img border=0 align=absmiddle src="http://www.ozones.com/forum/smile.gif">

Seems right to me. You may want to wrap those in a "for" loop instead of writing them all out by hand and incrementing the value but that should work fine.

Usually however you so want to create the objects on page load if you are going to manipulate existing elements on the page, instead of straight out of the Head


Walking the Earth like Kane

yeah, i WOULD use a for loop usually.
BUT...
im using a mix of programs.
and the program i am using (aptrix, if you've heard of it) stores pages which can be categorised and stuff, and then can dynamically generate a 'menu' that is customisable (eg a menu of sale items, or latest 10 news articles....) and i want a little dynamic layer next to each one....
let the fun begin!
wish me luck!

Man... I wish I had the slightest idea of what you guys were talking about. Well, maybe someday I'll get it. ????

well butcher, did you know that in javascript, you can create your own objects?
then, your objects can have properties, like the predefined ones do.
(eg window.height - height is a property of the object window)
so, lets say we want to create a chair:
thisChair = new Chair()

then, all you need is a function chair:
function Chair() {
this.price=20
this.weight=2
this.color='blue'}

so now, the value thisChair.color is 'blue'.
SO, that means you can create a few chairs:

thisChair = new Chair()
thatChair = new Chair()

right? but what if you dont want them to be all $20, 2kg and blue?
then pass variables!
check this:
function Chair(price, weight, color) {
this.price=price
this.weight=weight
this.color=color
}

SO.... then, when you create each chair, you give it its own variables:

thisChair = new Chair(20, 1, 'blue')
thatChair = new Chair(10, 5, 'pink')

so now, thisChair.price = 20, but thatChair.price = 10.
making sense?

ok, well, what i want to do is create, say 20 blocks objects.
but instead of writing
block1 = new Block(block1ID) //creates an object called 'block1', whose attributes are the block1ID
block2 = new Block(block2ID) //creates an object called 'block2', whose attributes are the block2ID
block3= new Block(block3ID) //creates an object......
and so on, i want it to do some writing for me.
so, as bitdamaged suggested, i can have something like this:
for(i=1, i>20, i++) {
eval('block' + i + ' = new Block(block' + i + 'id)')
}

so what this does create 20 block objects, block1, block2, etc..
the purpose of the eval function is to use the i variable to create a string, then evaluate that function as a string. understand?
if we just had blocki = new block(blockiID), then it would create the one "blocki" object. but the eval function basically means that when i=1, for instance, it writes this code:
block1 = new Block(block1id)
then evaluates it (runs the code), then it will do the same sort of thing for i=2, and so on.


....and that's what we were talking about.
and as for my later post, "yeah, i WOULD use a for loop usually.
BUT..." and so on,
well, that's an entirely different, non javascript, matter. im just using a program that makes my html.
i hope this helps.

Thank you Bunchapixels, That was a truly awesome explanation. Your explanation of creating an object was better than in any of the books I have paid for. My interest is piqued now though. If you ever get the chance, could you tell me what your doing with the 20 blocks? I find it much easier to understand things when I know why I would use them.

BTW: Sorry for the late reply, I didn't really expect anyone to answer my dumb interjection in your thread, but I'm greatfull you did.

ah, butcher, i thought you would never ask!
well, i learnt OOP (obj oriented prog) in uni, and thought "fantastic. now, where is this useful?"
ok, well, for work, i wanted to create this special bullets (you'll see in my example), and this obviously needed some OOPing, because they were all basically the same object, just different instances, with slightly different properties.
well, here's what i made: http://reitsma.tripod.com/divslider.htm
um, what else can i say?
i wont drown you with a barrage of links, just give you one: http://www.dkrz.de/~k202039/dhtml/index.html
this one has examples and explanation, and the code is nice and clean.

[This message has been edited by bunchapixels (edited 20-12-2000).]

I got them too http://www.bitdamaged.com let the smiley face catch up to your mouse and you'll see a bunch of individual objects




Walking the Earth like Kane

Me too, go here and see several different "instances" of one chaser "object":
http://bugimus.com/gurus/chaser_formation.html

Very cool guys! Bunchapixels, your divslider.htm wouldn't come up. I got the Tripod couldn't find the page, page(does that make sense, sense). The other link you gave me looks terrific, thankyou for pointing out more stuff I don't know that I need to learn, haha. I appreciate it.

http://reitsma.tripod.com/divslider.html
ok, i cut and paste it into the box, so if this doesnt work, i have no idea what is up.
far out! this is ridiculous!
i renamed it, maybe that will help: http://reitsma.tripod.com/stupidpage.html
ok, that seems to work.

[This message has been edited by bunchapixels (edited 21-12-2000).]

[This message has been edited by bunchapixels (edited 21-12-2000).]

Thanks Bunchapixels, That's a great effect. I'm also very flattered to see you renamed the page with me in mind. (stupidpage.html) I'll spend alot of time looking over your code trying to get it, Thanks for your help.

butcher - funny.
nah, it was renamed with tripod and the upload problem.
(ie, what should i rename this stupid bloody page to now?)

feel free to email me (or better yet put up another post to get some feedback from more educated persons), if you want me to explain the madness behind my methods.

Thanks, I may take you up on that.