how to get dynamic element for ajax - php

Question

I know i made lots of mistake thats why I come to here.
Actually I have some data
According to data I have Indication 1, Indication 2, Indication 3 and Indication 4, for each indication there is some message for user and if I select 2, 3 or 4 then the message will move to that corrosponding indication. And really I dont have idea how to do it becouse these message are coming from dynamicaly as:
$i=1;
while($row=mysqli_fetch_array($qry))
{
?>
<div class="solo"><div style=" width:100px;height:24px;float:left;padding:4px ;">
<select style="width:60px;font-size:14px;" onchange="move(this.value);">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<!--<option value="60min">60min</option>
<option value="other">other</option>-->
</select>
</div>
<div style=" width:600px;height:24px;float:left;padding-top:8px;text-align:center;"> <?php echo $row['message'];?></div>
<div style=" width:100px;height:24px;float:left;padding:4px ;">
<div style="width:100px; float:left;">
<input style="float:left;" type="checkbox" value="<?php echo $row['id']; ?>" id="<?php echo $row['id']; ?>" name="foo[]"/><div style="padding:2px; float:left;">Kill</div>
</div>
and I am using to get these message id
<script type="text/javascript">
function move(str)
{
var a=document.getElementsByClassName("mid")[0].value;
alert(a);
}
</script>
and i display this message id as in hidden text box:
<input type="hidden" name="msg" class="mid" value="<?php echo $row['id']; ?>">
am just confuse how to get a particuler message id for each message becouse above move() function is only giving one id by [0]
So I just want to know how to do this for each element when all the input box have same class.

Answer 1

If i understand correctly you want to iterate over the result list of getElementByClassName.
For this have a look at: https://stackoverflow.com/a/15843940/1885950
In your case it will look like:
var mid_holders = document.getElementsByClassName("mid");
for(var i = 0; i < mid_holders.length; i++)
{
alert(mid_holders.item(i).value);
}

Answer 2

document.getElementsByClassName("mid") gives you an array of dom elements. You are currently taking only the first element in that array. So loop through it and get each ones value attribute
function move(str) {
var a=document.getElementsByClassName("mid");
for(var i=0;i<a.length;i++)
alert(a[i].value);
}
update
Its not clear what you are trying to achieve.
If you are trying to alert the value of dom element with index as str, then the function could be as simple as
function move(str) {
alert(document.getElementsByClassName("mid")[str].value);
}
if not please mention what you are trying to achieve in your question.