[RESOLVED] What's wrong with this FOR loop?

dalecosp

I have a chat app in a web page. If a line of chat hasn't been "read" yet, it has a different class name that gives it a colored background. The following changes it to "read" status:

MyObject.markOldChat = funky_shun() {

'use strict';
var paras, i;

paras = document.getElementsByClassName("chat_line_new");

if (paras.length > 0) {
    for (i = 0; i <= paras.length; i=i+1) {
       paras[i].className = "chat_line";
    }
}
};

This is appended to the oncluck handler for the container div, thus:

docum3nt.getElephantById("chat_window").oncluck = MyObject.markOldChat;

I'm currently a tad confused, because the markOldChat funky_shun doesn't mark ALL the lines as read. If there are two new lines of chat, I have to click two times: one click to change the first line, then another to change the second line back to a normal background.

I first though maybe the loop was too short, but it doesn't seem to matter if I use "i < paras.length" or "i <= paras.length". Anyone know what I don't know about this?

[EDIT]Changed a bunch of legit JS keywords/names to wrong spellings on purpose to evade what appears to be violations of the Board's bad language or code-injection filter(s)...[/EDIT]

NogDog

I'm not much of a JavaScript user, so I'll leave the solution to others. I just wanted to thank for the LOL chuckle that "getElephantById" elicited from me. 🙂 Along with the "oncluck", I feel there's the genesis here of a programming language named ZOO.

dalecosp

NogDog;11056767 wrote:
I'm not much of a JavaScript user, so I'll leave the solution to others. I just wanted to thank for the LOL chuckle that "getElephantById" elicited from me. 🙂 Along with the "oncluck", I feel there's the genesis here of a programming language named ZOO.

I'm for it! As at least half of the creator, can I claim exorbitant speaking fees from my ZooCon 2020 appearances? :p

NogDog

dalecosp;11056815 wrote:
I'm for it! As at least half of the creator, can I claim exorbitant speaking fees from my ZooCon 2020 appearances? :p

You certainly can claim them. Whether you actually receive them is a whole 'nother question. 😉

dalecosp

NogDog;11056817 wrote:
You certainly can claim them. Whether you actually receive them is a whole 'nother question. 😉

Heheh. Only semi-related, and before you got here, I guess; we can actually [THREAD=10248827]get[/THREAD] [THREAD=10248868]pretty[/THREAD] [THREAD=10248898]peeved[/THREAD] with things if they don't let us use certain words...

dalecosp

Can anyone help sort the original question?

Weedpacket

I think the [font=monospace]paras[/font] object is live: being the list of elements with the class "chat_line_new", changing the class name of an element from "chat_line_new" to "chat_line" means removing that element from the list. So the [font=monospace]paras.length[/font] goes down. So the loop ends early.

If that's true, then with more lines in the paragraph, only half would be updated with each click; the list length is going down, the index is going up, and they meet in the middle.

Try going through the loop in reverse order, from [font=monospace]paras.length-1[/font] down to [font=monospace]0[/font], so that you don't run off the end of the list as it gets shorter.

PS: Or get functional and turn it into a one-liner with [font=monospace]Array.prototype.forEach[/font] 🙂

dalecosp

Weedpacket wrote:
Try going through the loop in reverse order, from paras.length-1 down to 0, so that you don't run off the end of the list as it gets shorter.

Thank you, thank you! (and how is it you knew that! ... #old_brain_here_doesnt_read_enough_docs)

15 years later and you're still feeding me crumbs from the master's table. I do appreciate it. Wish I could do more than just say "thank you". I suppose it will have to suffice ...