Javascript looping only through defined properties of array. How?

Posted by Beck on Stack Overflow See other posts from Stack Overflow or by Beck
Published on 2010-06-12T13:47:17Z Indexed on 2010/06/12 13:52 UTC
Read the original article Hit count: 151

Filed under:

JavaScript

|

loops

For example if i'm keeping array of references via id like that:

if(typeof channel_boards[misc.channel_id] == 'undefined') {

    channel_boards[misc.channel_id] = $('<div class="channel" channel_id="'+misc.channel_id+'"></div>').appendTo('#board');
}

And then i'm looping through array to find required reference. I'm looping through undefined properties as well. Is it possible to loop only through defined properties?

for(i=0;i<channel_boards.length;i++)
{
    if(channel_boards[i] != undefined)
    {
        if(channel_boards[i].attr('channel_id') != visible) {channel_boards[i].addClass('hidden_board');}
        else {channel_boards[i].removeClass('hidden_board');}       
    }
}

Maybe i should change the way i'm storing references? Via object for example, but how i'll be able to find proper reference via id number.

© Stack Overflow or respective owner

Related posts about JavaScript

CHAT ROOMs 7 by 6

as seen on Stack Overflow - Search for 'Stack Overflow'
I am looking for chatroom on one page with 7 loggedin users and 6+rows for say 42 users.these users will keep on adding wthnew users.Need urgent help.A PRETTY UNUSUAL Q FOR MOST OF U.What is MORE REQ new features: Usernames are unique to users currently chatting You can see a "currently chatting"… >>> More
Integrating JavaScript Unit Tests with Visual Studio

as seen on Stephen Walter - Search for 'Stephen Walter'
Modern ASP.NET web applications take full advantage of client-side JavaScript to provide better interactivity and responsiveness. If you are building an ASP.NET application in the right way, you quickly end up with lots and lots of JavaScript code. When writing server code, you should be writing… >>> More
Has Javascript developed beyond what it was originally designed to do?

as seen on Programmers - Search for 'Programmers'
I've been talking with a friend about the purpose of Javascript, when and how it should be used, etc. He quoted that: JavaScript was designed to add interactivity to HTML pages [...] JavaScript gives HTML designers a programming tool HTML authors are normally not programmers… >>> More
PHP, javascript, single quote problems with IE when passing variable from ajax post to javascript fu

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi! I have been trying to get this to work for a while, and I suspect there's an easy solution that I just can't find. My head feels like jelly and I would really appreciate any help. My main page.php makes a .post() to backend.php and fetches a list of cities which it echoes in the form of: <li… >>> More
Javascript in XSL that is loaded by Javascript

as seen on Stack Overflow - Search for 'Stack Overflow'
Is there anyway to have javascript run when a XSL sheet has been applied to an XML file by Javascript? I am using a JQuery plugin to apply the sheet to the xml but the javascript that is located inside of the XSL file will not run. I put the Javascript at the bottom of the file and it still does… >>> More

Related posts about loops

C++ behavior of for loops vs. while loops

as seen on Stack Overflow - Search for 'Stack Overflow'
As far as I understand, when you write a for-loop similar to this one for (int i = 0; i < SOME_NUM; i++) { if (true) do_something(); else do_something_else(); } The time complexity of this operation is mostly affected by the if (true) statement because the for-loop iterations don't… >>> More
While loops within while loops and output php?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a while loop to show the replies for a post on my website. The value for parentID used in the query is $post['postID'] which is an array of details for the post being viewed. As seen below it outputs the following (each subject is a link to view the full post) $q = $dbc -> prepare("SELECT… >>> More
Loops inside loops

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I'd like to find easier way to write loops inside loops. Here is example code of 3 levels of 'for' loops: int level = 0; int value = 0; bool next = false; for (int i0 = 0; i0 < 6; i0++) { level = 0; value = i0; method(); if (next) for (int i1 = 0; i1 < 6; i1++) … >>> More
Mulitple full joins in Postgres is slow

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a program to use the IMDB database and am having very slow performance on my query. It appears that it doesn't use my where condition until after it materializes everything. I looked around for hints to use but nothing seems to work. Here is my query: SELECT * FROM name as n1 FULL JOIN… >>> More
PL/SQL Practices - "On Cursor FOR Loops"

as seen on Oracle Technology Network - Search for 'Oracle Technology Network'
It's important to know when not to use cursor FOR loops. >>> More