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Javascript function needing to adjust multiple spans with the same ID

Posted on 2007-11-14
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Last Modified: 2008-02-01
I'm currently developing a web application for scientific paper database management system, and am having issues with an AJAX function that is supposed to update multiple divs with the same name.

Schema background in simple terms is as follows:

There are multiple [papers] inside a [project] - call these [project_papers]. There are also 0 to many [subprojects] within the [project]. In the case of the screenshot example below there are 2 subprojects. A [project_paper] can exist in multiple [subprojects] within the project, or in none at all. Each row representing a [project_paper] on the screen has a "pin", which kind of acts like a sticky row when the contents of the project are contracted (hiding the ones with the pin off). The pin is a span with an id and name of "pPaper{project_paper_id}", which is normally fine.

However, and this is where the problem exists, if the [project_paper] exists in two [subprojects] simultaneously, the span will of course have the same id and name as there is no differentiation between subprojects. Personally, I think this should be correct, and any javascript designed to update the contents of the span should apply to all instances on the page, but it only updates the top one - the database side of the AJAX fires correctly, and therefore the [project_paper] has the pin flag changed, but the display ends up confusingly incorrect.

Is there any way to update the javascript to update the content of both spans?

Screenshot example (rows in yellow are the one with the same id -- pin is red thing on the left):

http://rdms.powerwatch.org.uk/rdms1.png

Screenshot example with changed pin (top row pin changed but not bottom row):

http://rdms.powerwatch.org.uk/rdms2.png

HTML that calls the javascript function:

----------
<span name="pPaper<%=CLng(RS("project_paper_id"))%>" id="pPaper<%
  =CLng(RS("project_paper_id"))%>"><img src="/images/buttons/pin_<%
  =projPaperPin%>.gif" border="0" onClick="setProjectPin(<%
  =CLng(RS("project_paper_id"))%>,<%=theUID%>)" /></span>
-----------

Javascript functions:

-----------
/* Adjusts the pin status of a project paper within project or subproject for the active user */

var projPapPin;

function setProjectPin(projectPaperID,userID)
{
  projPapPin = projectPaperID;
  xmlHttp=GetXmlHttpObject();

url="/includes/ajax/ch_projectpin.asp?projPaperID="+projectPaperID+"&userID="+userID+"&sid="+Math.random();
  xmlHttp.onreadystatechange=displayProjectPin;
  xmlHttp.open("GET",url,true);
  xmlHttp.send(null);
}

function displayProjectPin()
{
  if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
  {
    document.getElementById('pPaper'+projPapPin).innerHTML = xmlHttp.responseText;
  }
}
-----------
0
Comment
Question by:topazg
  • 2
3 Comments
 
LVL 19

Accepted Solution

by:
nschafer earned 500 total points
Comment Utility
Your problem is that Element ID's should be unique and Javascript assumes that they are.  So when you use getElementById() you are only getting the first element with that ID.  You may want to try using getElementsByName.  This will return a collection of elements with the name and you can then loop through them updating the innerHTML.

I hope this helps,
Neal.

example:
------------------------------------------------------------
function displayProjectPin()
{
  if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
  {
    var el = document.getElementsByName('pPaper'+projPapPin);
    for (i=0;i<el.length;i++)
    {
        el[i].innerHTML = xmlHttp.responseText;
    }
  }
}

------------------------------------------------------------
0
 
LVL 3

Author Comment

by:topazg
Comment Utility
Awesome, works perfectly, many thanks :)

I've updated the id to pPaper{paper_project_id}Sub{subproject_id} and left the name as it is, adopting your code example.

Thanks for the fast response!
0
 
LVL 19

Expert Comment

by:nschafer
Comment Utility
Glad I could help,

Neal.
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