getElementsByTagName

not working well

[mcibor]

I have many selects populated by database with php:
<select name="sort[]">....<select name="sort[]">...

What I want is to get to each of them. i know how many there are and therefore I thought that this'll do:

frm = document.getElementsByTagName("form");
sel = document.getElementsByTagName("select");

function my {
variable = frm[0].sel[0].value;
//some operation ion variable
frm[0].sel[0].value = variable;//and similar stuff for other selects
}

However Mozilla gives me an error: frm[0].sel has no properties.
Where did I make a mistake?
Best regards
Michal Cibor

[RonPK]

It may help to declare frm and sel as global variables:
var frm = ...
var sel = ...
Otherwise they may not be available within the scope of a function.

Also I'd prefer to use something like this to loop through the forms:

var frms = document.getElementsByTagname("form"); 
function myfunction() { 
 var sels; 
 for (var i=0; i< frms.length; i++) { 
  sels = frms[i].getElementsByTagName("select"); 
  // loop through the selects in a similar manner 
 } 
}

[Rambo Tribble]

I believe RonPK has the solution with the looping constuct. Doing as you have, you have two separate and unrelated arrays.

[mcibor]

so you mean that sel[0] is really document.form.select? That explains things a bit.
Thanks a lot!

Michal Cibor

[Rambo Tribble]

Actually, sel[0] isn't exactly attached to a single form in this reference. sel[0] is simply the first select to appear on the page, regardless of how many forms are declared. The value returned by getElementsByTagName('select') is just an array of selects, with no particular reference to anything but the order in which they appear on the page.

[mcibor]

It didn't help.
This is the version:

var frm = document.getElementsByTagName("form");
var sel = frm[0].getElementsByTagName("select");

function js_saveTxt()
{
var f = sel[0].value + "%2" +
sel[1].value + "%2";
}

And the error is:
Error: frm[0] has no properties
In line 2

What to do? I'm no expert in javascript. I just want to go through all selects on one form.

Hope to hear from you
Michal Cibor

[mcibor]

I think I found the problem now. Omitting the form was a right thing to do. Now the code looks like this:

var sel = document.getElementsByTagName("select");

function js_saveTxt()
{
var f = sel[0].value + "%2" +
sel[1].value + "%2";
}

And this works.

Thanks all!
Michal Cibor