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Select tag HTML dynamic javaScript PHP

Hello I want to achieve is to make "Select Form HTML" dynamic using JavaScript, What I mean by that is I expect every time I select a dropdown must be selected the value that I set to that tag.
The data from tag is from database I loop the data using php
ex. 1 src: Get selected value/text from Select on change
This example is 100% working correct but what I need is not to get the value but to assign like sample below next example 2
function handleSelectChange(event) {
var selectElement = event.target;
var value = selectElement.value;
alert(value);
}
<select onchange="handleSelectChange(event)">
<option value="1">one</option>
<option value="2">two</option>
</select>
ex 2 Those function will alert or run everytime I select/Click each of them F1 or F2
<table>
<tr>
<td onclick="myFunction1()">F1</td>
<td onclick="myFunction2()">F2</td>
</tr>
</table>
<script>
// Function 1 will run when I click the F1
function myFunction1() { alert('myFunction1'); }
// Function 2 will run when I click the F2
function myFunction2() { alert('myFunction2'); }
In example 1 As you can see the first example select form html will grab the the value of option tag, right?.
Now In example number 2 it will run the function when I click each of the F1 or F2
So what I need to the program is pass a value from my database to my javaScript function and run it like in alert or example 1 but in "Select tag" HTML version
ex. 3 Here's my query
<form action="">
<select name="customers" id="myId" class="form-control">
<option value="">Select a customer:</option>
<?php
$user_id = 1;
$sql = "SELECT * FROM `myTable` WHERE user_id = '$user_id' Order by create_at DESC";
$result = $mysqli->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc())
{ ?>
<!-- appsFunction('<?php echo $row['colName2']; ?>') << will be the value that should run in console.log -->
<option value="<?php echo $row['id']; ?>" onclick="appsFunction('<?php echo $row['colName2']; ?>')"><?php echo $row['colName1']; ?></option>
<?php }
} else { return false; }
?>
</select>
</form>
ex. 3 part 2 javascript
<script>
function appsFunction(passVar) {
colose.log(passVar);
}
</script>
As you can see in my first example a "Select Tag" HTML when I select dropdown it returns to me a value right?, in second example when I click F1 or F2 it will run the function then return alert, What I need here is When I select the dropdown it will accept the value I pass in function "appsFunction(passVar)" appsFunction('<?php echo $row['colName2']; ?>') from select tag which the value is from my database.. so I need help idea how to do that properly..
NOTE: The function must be run when I select the dropdown, the function must be accept the value I set which from my database it's like totally example number 2 but in Select tag HTML version not just text or html table.
Thanks in advance for solving my problem.

If you register an event handler on the select element itself that listens for change events you will be able to process the selected OPTION and access any value/property associated with it. You cannot assign an event handler directly to an OPTION element as you are trying to do here. You can add as many dataset attributes as you need to the OPTION elements however which you can easily access in the Javascript event handler.
If the value you pass into the SQL statement is to be dynamic ( from a GET or POST request most usually ) you really need to use a Prepared Statement to help mitigate SQL Injection attacks.
As your select menu is making use of only 3 columns from the mytable table you should limit the returned fields to those columns which in turns helps when using a Prepared Statement as you can easily assign the results as variables.
<form name='geronimo'>
<select name="customers" class="form-control">
<option selected hidden disabled>Select a customer:
<?php
$user_id = 1;
$sql="select `id`, `colName1`, `colName2` from `mytable` where user_id = ? order by create_at desc";
$stmt=$mysqli->prepare($sql);
$stmt->bind_param('s',$user_id);
$res=$stmt->execute();
if( $res ){
$stmt->bind_result($id,$col1,$col2);
while( $stmt->fetch() ){
printf('<option value="%s" data-col="%s">%s', $id, $col2, $col1 );
}
$stmt->free_result();
$stmt->close();
}
?>
</select>
</form>
<script>
document.forms.geronimo.customers.addEventListener('change',function(e){
let id=this.value;
let col2=this.dataset.col;
let col1=this.options[this.options.selectedIndex].text;
alert( id + ' ' + col2 + ' ' + col1 )
});
</script>

how to create several select drop down listbox using php

I am new to php, I would like to generate the same select drop down list box.
This is the code I have, but it only works for the first drop down, not for the second one...
This is the code I am using without any success :
<?php
while($row = mysqli_fetch_array($result))
{
$output .= '
<tr>
<td>'.$row["id"].'</td>
<td class="last_name" >
<select id="t1"><option>'.$row["t1"].'</option>';
while($rowcode=mysqli_fetch_array($resulttasks))
{ $output .= '<option value="'.$rowcode["id"].'">'.$rowcode["code"].'</option>' ; }
$output .='</select>
</td>
<td class="last_name" >
<select id="t2"><option>'.$row["t2"].'</option>';
while($rowcode=mysqli_fetch_array($resulttasks))
{ $output .= '<option value="'.$rowcode["id"].'">'.$rowcode["code"].'</option>'; }
$output .='</select>
</td>
</tr>';
?>
Thanks in advance for the help !

Duplicate identifiers is not the issue, before the second loop of "t2" select, try putting mysqli_data_seek($resulttasks,0);
Explanation:
duplicate identifiers are only for DOM and it has nothing to do with parsing HTML in PHP. If you guys notice, he is using the same result set two times, PHP does not run another loop on same data once process already. So, we have to reset to 0th row if we want to run another loop on the same result set.

The id attribute must be unique, replace the duplicate ones by common classes :
<select id="t1">
Must be :
<select class="t1">
So when you loop through the $result you'll not generate duplicate identifiers.

hope this helps you
change your id with loop
example
$index = 1;
for($i = 0; $i < $count_array; $i ++) {
echo '<select id="t1' . $index . '"></select>';
$index ++;
}

Arrays from 2 MySQL queries to be used on 2 select using javascript

I already have the first HTML select populated by the result of the first query.
Now what I need or want to do is put the results from the second query on a Json file (maybe) or an XML (don't care) and then using javascript (not jquery) populate the second HTML select based on the first HTML select option selected.
This is my current code:
<?php
# Get all brands id and brand name to populate brands HTML select 1
$q1=mysqli_query($conect,"SELECT id, brand FROM brands ORDER BY brand ASC");
$brand_select="";
while($brand=mysqli_fetch_assoc($q1)){
$brand_select=$brand_select.'<option value="'. $brand['id'] .'">'. $brand['brand'] .'</option>';
}
# Get all models id and model name to populate models HTML select based on the brands ID from html select 1
$q2=mysqli_query($conect,"SELECT id, brand_id, model FROM models ORDER BY model ASC");
$models_select="";
while($model=mysqli_fetch_assoc($q2)){
$models_select=$models_select.'<option value="'. $model['id'] .'">'. $model['modelo'] .'</option>';
}
?>
<select name="brand" id="brands" class="s1" onchange="populate(this.id,'modelos')">
<option value="">Select Brand</option>
<?= $brand_select ?>
</select>
<br>
<select name="models" id="models" class="s1">
<option value="">Select Model</option>
<?= $models_select ?>
</select>
The id from the brands table is related to the brand_id on the models table for relational purposes.
The brands HTML select are displaying the brands just perfect as it should and the options as is, are showing the full list of models of all brands.
I'm sure that an onChange event should be used on the first HTML select, that is as far as I can get without Javascript.
Of course I've looked other Similar Questions but can't find one that matches my idea about this.
Any suggestion from You the real genius :-)

Here is one way of doing it. PHP is used to produce an array of model options sorted by brand - this makes things easier for the JavaScript. An event listener is added to the brands select which updates the models select appropriately.
PHP
$q1=mysqli_query($conect,"SELECT id, brand FROM brands ORDER BY brand ASC");
$brand_select="";
while($brand=mysqli_fetch_assoc($q1)){
$brand_select=$brand_select.'<option value="'. $brand['id'] .'">'. $brand['brand'] .'</option>';
}
# Get all models id and model name to populate models HTML select based on the brands ID from html select 1
$q2=mysqli_query($conect,"SELECT id, brand_id, model FROM models ORDER BY brand_id, model ASC");
$models_select="";
while($model=mysqli_fetch_assoc($q2)){
$models_select[$model['brand_id']][] = '<option value="'. $model['id'] .'">'. $model['model'] .'</option>';
}
echo "<script type=\"text/javascript\">\nvar models = {};\n";
foreach ($models_select as $b => $m) {
echo "models['$b'] = '" . implode('', $m) . "';\n";
}
echo '</script>';
Javascript
window.addEventListener('load', function () {
document.getElementById('brands').addEventListener('change', function () {
if (this.value != '') {
document.getElementById('models').innerHTML = '<option value="">Select Model</option>' + models[this.value];
}
});
});
HTML
<select name="brand" id="brands" class="s1">
<option value="">Select Brand</option>
<?= $brand_select ?>
</select>
<br>
<select name="models" id="models" class="s1">
<option value="">Select Model</option>
</select>

Easy solution is:
Create a php array with all the models that you then write into a javascript array:
$models = [];
while($model=mysqli_fetch_assoc($q2)){
$models_select=$models_select.'<option value="'. $model['id'] .'">'. $model['modelo'] .'</option>';
$models[] = $model;
}
?>
<script>
var moduls = <?php echo json_encode($models); ?> // this makes a JSON string out of the php array, which js can interpret as javascript array/object.
function populateModels(brandId) {
// TODO:
// filter the models that have the right brandId
// generate the options of the fitting models
// write the options to select #models
}
</script>
A better (because you don't have massive data lying around that you possibly don't use) solution would be to use ajax, as you can find in many questions/answers for "Dynamic selects"

Sending a different column instead of this.value in php to javascript function (Query)

I've made a select list and filled it with info from a DB. Now i'm trying to make it so whenever you select a different item in the list it calls a javascript function that checks if the selected item/entity (or whatever it's supposed to be called) has a comment or not, and reacts accordingly.
So far I have this, which does work, and only shows the paragraph if the ID of the selected item sent is over 5. However, I don't know how to send the comment that is in the query as the parameter, so that it can then check the length and react.
This is what I have so far:
// Create connection
$conn = mysql_connect("localhost", "root", "admin")
or die("Could not connect: " . mysql_error());
// Selecting the DB
mysql_select_db("tickets") or die("Could not connect: " . mysql_error());
$query = mysql_query("SELECT * FROM tickets order by ID");
$numrows = mysql_num_rows($query);
//I want to change this.value to be the selected item's comment
echo '<select name="Tick" size='.$numrows.' onChange="checkSelectedValue(this.value)">';
while ($row = mysql_fetch_array($query)) {
echo '<option value="'.$row['ID'].'">Comment: '.$row['comments'].' </option>';
}
echo '</select>';
echo '<p id="commentNotifier" style='display:none;'> Selected item has a comment. </p>';
How would I modify this so the parameter of onChange="checkSelectedValue(this.value)" would be the selected item's comment instead of this.value which is, in my case, the ID.
Note that I don't want to change the value of each option to be comments instead of ID.
This is the javascript functon that works with the ID sent, and if it is over 5 it shows the paragraph that's otherwise hidden:
<script type="text/javascript">
function checkSelectedValue(val){
var element=document.getElementById('commentNotifier');
if(val > 5) //I would change this to val.length > 0 to check if comments exists or not
element.style.display='block';
else
element.style.display='none';
}
</script>
Pretty straightforward function. Cheers in advance!

In a pure javascript solution the best answer of this stack would helps : Get selected value in dropdown list using JavaScript?

You can use this to select the comment from the dropdown:
$('#mySelect').find(":selected").text()
But it requires you to use jQuery
Working fiddle: https://jsfiddle.net/b1qjw214/
In pure javascript:
function findElem() {
var elem = document.getElementById("mySelect");
var elemTxt = elem.options[elem.selectedIndex].text;
}
Fiddle: https://jsfiddle.net/dsy3tgmy/

Use data-* attributes and instead of this.value, pass this as argument so that you can deal with element and all its attributes.
Element.dataset returns the object of all the data-* attributes of the element
Try this:
function checkSelectedValue(elem) {
console.log('Value: ' + elem.value);
console.log('Comment: ' + elem.options[elem.selectedIndex].dataset.comment);
}
<script src="http://gh-canon.github.io/stack-snippet-console/console.min.js"></script>
<select onChange="checkSelectedValue(this)">
<option data-comment='Comment goes here' value="volvo">Volvo</option>
<option data-comment='Comment goes here' value="saab">Saab</option>
<option data-comment='Comment goes here' value="mercedes">Mercedes</option>
<option data-comment='Comment goes here' value="audi">Audi</option>
</select>

Multiple dependent dynamic select boxes in form

There is a model A that has_many B and a form where one can create a new A and
add/remove Bs. I.e. there is a link Add new B that runs some Javascript to insert another partial where one fills in values for B. All works fine.
The problem
Specifying a B is done through selecting the values using a couple of select
boxes. The problem is that depending on a value selected in one, the
collections used in the other selects should be scoped to only show relevant options. It's the classic case
with dynamic select boxes (think country - state select boxes), only with more
select boxes and I'd like all the select boxes to appear initially, so the
user can start from anywhere (select state first and country select box
narrows down its collection to the ones that can be chosen for that state).
Current approach
The Bs are rendered in a table, one B per row and I was thinking that I could
use AJAX to replace the table row (content) after fetching the new collections
from the server. This obviously needs a couple of things in place.
tr tag must have a unique id attribute, so replace_html can be used.
need to have a trigger on change for each select box
need to pass all select boxes' values (for that row) to the server
I'm stuck here, because of the following:
adding a B needs to have something unique to identify the tr tag as well
as all the selects on that row. I can use Time.now.to_i but that won't
work for the Javascript run by the link to add a new B because that will
hardcode the value and all use the same.
not sure if I should go with observe_field or a remote call in the select
form field helper.
how to pick up the values of all selects in one row and pass that remotely
to the server when triggered?
The project I'm working on is Rails 1.2.3 and uses Prototype. Please feel free to post "newer" solutions too, because I'm curious to see different solutions.
Any help on this is highly appreciated. Thanks in advance!

This doesn't answer your entire question but it might get you started. I handle it like this... this is for playlist entry, where the user can add new forms in a div #playlist-entry, and each form is .new_song_form with a hidden field .form_num (which I use in the create.js.erb file to tell it which form to hide/warn of validation errors, which isn't really relevant for you I guess).
var form_counter = 1;
function addSongFields() {
playlistEntry = $('#playlist-entry');
playlistEntry.append("<%= escape_javascript(render :partial => 'playlist_entry_form', :locals => { :schedule_event => #schedule_event, :playlist_entry => PlaylistEntry.new }) %>");
playlistEntry.find('.new_song_form:last').attr('id', 'new_song_form_'+form_counter);
playlistEntry.find('.form_num:last').val('new_song_form_'+form_counter);
}
$(document).ready(function() {
$('#add-song-link').click(function(event) {
event.preventDefault();
addSongFields();
form_counter++;
});
});
This form is a little different because there's no one "major" form to submit, it's a bunch of forms all on one page, but this basic idea might help you. It's not perfect programming - for example I should be passing form_counter as an argument to the function... but it works perfectly.

Dynamic Dependent Select Boxes
How to create dependent drop down list in php? I have searched a lot then implemented this one. This is created using HTML, JS, PHP simple dependent drop down boxes.
I knew it was possible to create a dynamic dependent drop down form using PHP, MySQL, and JavaScript,
but I had never had an excuse to use one before I need to teach to my students.
<?php
$region = $country = $state = $city = null; //declare vars
$conn = mysql_connect('localhost', 'username', 'password');
$db = mysql_select_db('selects',$conn);
if(isset($_GET["region"]) && is_numeric($_GET["region"]))
{
$region = $_GET["region"];
}
if(isset($_GET["country"]) && is_numeric($_GET["country"]))
{
$country = $_GET["country"];
}
if(isset($_GET["state"]) && is_numeric($_GET["state"]))
{
$state = $_GET["state"];
}
if(isset($_GET["city"]) && is_numeric($_GET["city"]))
{
$city = $_GET["city"];
}
?>
<script language="JavaScript">
function autoSubmit()
{
var formObject = document.forms['theForm'];
formObject.submit();
}
</script>
<form name="theForm" method="get">
<!-- REGION SELECTION -->
<select name="region" onChange="autoSubmit();">
<option value="null"></option>
<option VALUE="1" <?php if($region == 1) echo " selected"; ?>>East</option>
<option VALUE="2" <?php if($region == 2) echo " selected"; ?>>West</option>
</select>
<br><br>
<!-- COUNTRY SELECTION BASED ON REGION VALUE -->
<?php
if($region != null && is_numeric($region))
{
?>
<select name="country" onChange="autoSubmit();">
<option VALUE="null"></option>
<?php
//POPULATE DROP DOWN MENU WITH COUNTRIES FROM A GIVEN REGION
$sql = "SELECT COUN_ID, COUN_NAME FROM COUNTRY WHERE RE_ID = $region";
$countries = mysql_query($sql,$conn);
while($row = mysql_fetch_array($countries))
{
echo ("<option VALUE=\"$row[COUN_ID]\" " . ($country == $row["COUN_ID"] ? " selected" : "") . ">$row[COUN_NAME]</option>");
}
?>
</select>
<?php
}
?>
<br><br>
<?php
if($country != null && is_numeric($country) && $region != null)
{
?>
<select name="state" onChange="autoSubmit();">
<option VALUE="null"></option>
<?php
//POPULATE DROP DOWN MENU WITH STATES FROM A GIVEN REGION, COUNTRY
$sql = "SELECT STAT_ID, STAT_NAME FROM states WHERE COUN_ID = $country ";
$states = mysql_query($sql,$conn);
while($row = mysql_fetch_array($states))
{
echo ("<option VALUE=\"$row[STAT_ID]\" " . ($state == $row["STAT_ID"] ? " selected" : "") . ">$row[STAT_NAME]</option>");
}
?>
</select>
<?php
}
?>
<br><br>
<?php
if($state != null && is_numeric($state) && $region != null && $country != null)
{
?>
<select name="city" onChange="autoSubmit();">
<option VALUE="null"></option>
<?php
//POPULATE DROP DOWN MENU WITH CITIES FROM A GIVEN REGION, COUNTRY, STATE
$sql = "SELECT CIT_ID, CITY_NAME FROM CITY WHERE STAT_ID = $state ";
$cities = mysql_query($sql,$conn);
while($row = mysql_fetch_array($cities))
{
echo ("<option VALUE=\"$row[CIT_ID]\" " . ($city == $row["CIT_ID"] ? " selected" : "") . ">$row[CITY_NAME]</option>");
}
?>
</select>
<?php
}
?>
</form>