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How to preselect in multiselect box [duplicate]

This question already has answers here:
Javascript/jQuery: Set Values (Selection) in a multiple Select
(9 answers)
Closed 3 years ago.
I want to preselect of id (195,197,120) by code on load
in multiselect box
coresponding id 195,197,120 will preselected
<select class="width100" id="dialog_settings_event_selected_recipient" style="height:80px;" multiple="multiple">
<option value="120">Aaban bilal</option>
<option value="197">Aabid iqbal</option>
<option value="196">Aadan parvaiz shah</option>
<option value="262">Aadil bashir</option>
<option value="195">Aaksa iqbol</option>
<option value="233">Aamir shabir</option>
<option value="231">Aasma zahoor</option>
<option value="198">Aathir shah bhat</option>
<option value="208">Aatif dar</option>
<option value="244">Aatif manzoor</option>
<option value="77">Abrar Mushtaq</option>
<option value="68">Adnan Javid</option>
<option value="236">Adnan amin</option>
<option value="132">Adnan iqbal</option>
<option value="112">Adnan mushtaq pir</option>
<option value="252">Adnan nazir-107</option>
<option value="157">Afhan Mudasir</option>
<option value="154">Ahsan Yousuf</option>
<option value="87">Aijaz Ah Malik</option>
</select>

Try this to set values for multiple select
var data="120,197,195";
//Make an array
var dataarray=data.split(",");
// Set the value
$("#dialog_settings_event_selected_recipient").val(dataarray);
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select class="width100" id="dialog_settings_event_selected_recipient" style="height:80px;" multiple="multiple">
<option value="120">Aaban bilal</option>
<option value="197">Aabid iqbal</option>
<option value="196">Aadan parvaiz shah</option>
<option value="262">Aadil bashir</option>
<option value="195">Aaksa iqbol</option>
<option value="233">Aamir shabir</option>
<option value="231">Aasma zahoor</option>
<option value="198">Aathir shah bhat</option>
<option value="208">Aatif dar</option>
<option value="244">Aatif manzoor</option>
<option value="77">Abrar Mushtaq</option>
<option value="68">Adnan Javid</option>
<option value="236">Adnan amin</option>
<option value="132">Adnan iqbal</option>
<option value="112">Adnan mushtaq pir</option>
<option value="252">Adnan nazir-107</option>
<option value="157">Afhan Mudasir</option>
<option value="154">Ahsan Yousuf</option>
<option value="87">Aijaz Ah Malik</option>
</select>

how to validate userinput with javascript

I have this scenario where i have 4 drop down boxes, where you can choose CM for a carport and a shed, within that carport.
I want to prompt the user with messages/errors in these scenarios:
the shed is chosen to be wider than it is long.
the shed is atleast 60cm smaller than the carports in both width and length
only one of the sheds dimensions being chosen
the form looks like this
<form name="createorder" action="FrontController" method="POST">
<input type="hidden" name="command" value="createorder">
<br>
Length of shed:<br>
<select name="lengthShed">
<option value="0">I do not want a shed</option>
<option value="180">180cm</option>
<option value="210">210cm</option>
<option value="240">240cm</option>
<option value="270">270cm</option>
<option value="300">300cm</option>
<option value="330">330cm</option>
<option value="360">360cm</option>
<option value="390">390cm</option>
<option value="420">420cm</option>
<option value="450">450cm</option>
<option value="480">480cm</option>
<option value="510">510cm</option>
<option value="540">540cm</option>
<option value="570">570cm</option>
<option value="600">600cm</option>
<option value="630">630cm</option>
<option value="660">660cm</option>
<option value="690">690cm</option>
<option value="720">720cm</option>
</select>
<br>
Width of shed:<br>
<select name="widthShed">
<option value="0">I do not want a shed</option>
<option value="18=">180cm</option>
<option value="210">210cm</option>
<option value="240">240cm</option>
<option value="270">270cm</option>
<option value="300">300cm</option>
<option value="330">330cm</option>
<option value="360">360cm</option>
<option value="390">390cm</option>
<option value="420">420cm</option>
<option value="450">450cm</option>
<option value="480">480cm</option>
<option value="510">510cm</option>
<option value="540">540cm</option>
<option value="570">570cm</option>
<option value="600">600cm</option>
<option value="630">630cm</option>
<option value="660">660cm</option>
<option value="690">690cm</option>
</select>
<br>
Width:<br>
<select name="width">
<option value="240">240cm</option>
<option value="270">270cm</option>
<option value="300">300cm</option>
<option value="330">330cm</option>
<option value="360">360cm</option>
<option value="390">390cm</option>
<option value="420">420cm</option>
<option value="450">450cm</option>
<option value="480">480cm</option>
<option value="510">510cm</option>
<option value="540">540cm</option>
<option value="570">570cm</option>
<option value="600">600cm</option>
<option value="630">630cm</option>
<option value="660">660cm</option>
<option value="690">690cm</option>
<option value="720">720cm</option>
<option value="750">750cm</option>
</select>
<br>
Length:<br>
<select name="length">
<option value="240">240cm</option>
<option value="270">270cm</option>
<option value="300">300cm</option>
<option value="330">330cm</option>
<option value="360">360cm</option>
<option value="390">390cm</option>
<option value="420">420cm</option>
<option value="450">450cm</option>
<option value="480">480cm</option>
<option value="510">510cm</option>
<option value="540">540cm</option>
<option value="570">570cm</option>
<option value="600">600cm</option>
<option value="630">630cm</option>
<option value="660">660cm</option>
<option value="690">690cm</option>
<option value="720">720cm</option>
<option value="750">750cm</option>
<option value="780">780cm</option>
</select>

Bind a function to your <select> elements onchange property.
let selects = document.querySelectorAll('select');
for(var i = 0; i < selects.length; i++){
selects[i].onchange = function(){
// Check for your conditions
// If your warning conditions are met, prompt user
}
}
That is, assuming you want the validation to happen when the user changes one of the select's values.
If you want to validate with a button click, you can instead bind the function to the click event of the button.
let button = document.getElementById(buttonID);
button.onclick = function(){
// Check for your conditions
// If conditions are met, prompt user
}
To prompt the user, you can use a simple alert() to which you pass your message. Or make a more elaborate function to do something custom.
As for your conditions, that sounds like commercial math. Might have to split your question in multiple questions here as there are a lot of possible awnsers.
It might be easier for you to add IDs to your selects so you can get them via document.getElementById(idString). You can then get their value through document.getElementById(idString).value. And to use it in math solving, you will need to parse the string that the <select> will return as value, like so parseInt(document.getelementById(idString).value).

If select option value matches text in separate div, add disabled field

I'm using a select field on my site which reloads the page and then adds this to value to a separate div. I want to be able to disable this option if any of the divs have the same value as the option.
<select id="bayname" name="bayname">
<option value="">--Select Bay--</option>
<option value="1">Bay 1</option>
<option value="2">Bay 2</option>
<option value="3">Bay 3</option>
<option value="4">Bay 4</option>
<option value="5">Bay 5</option>
<option value="6">Bay 6</option>
<option value="7">Bay 7</option>
<option value="8">Bay 8</option>
<option value="9">Bay 9</option>
<option value="10">Bay 10</option>
<option value="11">Bay 11</option>
<option value="12">Bay 12</option>
<option value="13">Bay 13</option>
<option value="14">Bay 14</option>
<option value="15">Bay 15</option>
<option value="16">Bay 16</option>
<option value="17">Bay 17</option>
<option value="18">Bay 18</option>
<option value="19">Bay 19</option>
<option value="20">Bay 20</option>
<option value="21">Bay 21</option>
<option value="22">Bay 22</option>
<option value="23">Bay 23</option>
<option value="24">Bay 24</option>
<option value="25">Bay 25</option>
<option value="26">Bay 26</option>
<option value="27">Bay 27</option>
<option value="28">Bay 28</option>
<option value="29">Bay 29</option>
<option value="30">Bay 30</option>
</select>
For example if a user clicks on 'Bay 1' a div will be created like this:
<li id="1509013949" class="cart-select cart-mode-cart">
1
</li>
And then when the page reloads again, i want to create an if statement so if the value from the select is within one of the divs then it should add it as disabled.
I've had ago at doing this using the code below and i can't get it to print out in the console log.
var baynumberoption = $("#bayname option").val();
var baynumber = $(".cart-select a[href='#select']").text();
if (baynumber.indexOf(baynumberoption) >= 0) {
console.log("match found");
}

$("#bayname option") returns all of the options so I think you really want to use the following. Note if you don't want to rely on the inner text of the link, you can also add data attribute like data-id="1" to store the value which can be used like:
$("#bayname option").each(function() {
var val = $(this).val();
if ( $(".cart-select a[data-id=" + val + "]").length > 0 ) {
$(this).attr("disabled", "disabled");
}
});
Some of the syntax may be off but you get the idea.

Scroll down to selected option on button click using jquery

I have a list of countries like this:
The list is very extensive. I need to be able on a button click to move (focus) to the specified country.
There are many threads in StackOverflow but none of them worked. For example I tried this:
var code = 40;
$('#id_resource-regions').val(code).scrollTop(160);
There is no response and no error/warnings in the developers tool.
Note that the list is created using django forms and templates.

Select the option element you are looking for.
Get the offset top position using .offset(), of the selected option element.
Get the offset top of the select element.
Use .scrollTop() to scroll to the desired option.
Here is an example
var btn = $('button')
var select = $('select')
btn.on('click', function() {
var option = select.find("option:contains('item-30')");
var optionTop = option.offset().top
var selectTop = select.offset().top;
select.scrollTop(select.scrollTop() + (optionTop - selectTop));
option.prop('selected', true)
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select name="" id="select" multiple="multiple">
<option value="">item-1</option>
<option value="">item-2</option>
<option value="">item-3</option>
<option value="">item-4</option>
<option value="">item-5</option>
<option value="">item-6</option>
<option value="">item-7</option>
<option value="">item-8</option>
<option value="">item-9</option>
<option value="">item-10</option>
<option value="">item-11</option>
<option value="">item-12</option>
<option value="">item-13</option>
<option value="">item-14</option>
<option value="">item-15</option>
<option value="">item-16</option>
<option value="">item-17</option>
<option value="">item-18</option>
<option value="">item-19</option>
<option value="">item-20</option>
<option value="">item-21</option>
<option value="">item-22</option>
<option value="">item-23</option>
<option value="">item-24</option>
<option value="">item-25</option>
<option value="">item-26</option>
<option value="">item-27</option>
<option value="">item-28</option>
<option value="">item-29</option>
<option value="">item-30</option>
<option value="">item-31</option>
<option value="">item-32</option>
<option value="">item-33</option>
<option value="">item-34</option>
<option value="">item-35</option>
<option value="">item-36</option>
<option value="">item-37</option>
<option value="">item-38</option>
<option value="">item-39</option>
<option value="">item-40</option>
</select>
<button>move to item 30</button>

Month selection dropdown in HTML and JavaScript

I have 2 drop downs in HTML both representing months. So I want a validation like following.
If I select the first drop down month as April, then the next drop-down menu should start from the month April. If the first one is changed to June then the second should change to June.
<div id="head2" style="width:15%;float:right;margin-left:5px;">
<select id='gMonth2' onchange="show_month()">
<option value=''>--Select Month--</option>
<option selected value='1'>Janaury</option>
<option value='2'>February</option>
<option value='3'>March</option>
<option value='4'>April</option>
<option value='5'>May</option>
<option value='6'>June</option>
<option value='7'>July</option>
<option value='8'>August</option>
<option value='9'>September</option>
<option value='10'>October</option>
<option value='11'>November</option>
<option value='12'>December</option>
</select>
</div>
<div id="head1" style="width:15%;float:right;margin-left:5px;">
<select id='gMonth1'>
<option value=''>--Select Month--</option>
<option selected value='1'>Janaury</option>
<option value='2'>February</option>
<option value='3'>March</option>
<option value='4'>April</option>
<option value='5'>May</option>
<option value='6'>June</option>
<option value='7'>July</option>
<option value='8'>August</option>
<option value='9'>September</option>
<option value='10'>October</option>
<option value='11'>November</option>
<option value='12'>December</option>
</select>
</div>
The function will be:
function show_month()
{
//
}
How should I write that function?

Easy with jQuery:
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js" type="text/javascript"></script>
<script>
$(function(){
$('#gMonth2').change(function(){
var month = $(this).val();
$('#gMonth1').val(month);
});
});
</script>
and skip the onChange event in the first select...
Working example here: http://jsfiddle.net/sCnEZ/1/

Your JS function could be like this:
function show_month(obj) {
document.getElementById('gMonth1').selectedIndex = obj.selectedIndex;
}
You should change onchange="show_month()" with onchange="show_month(this)"
Check out this jsfiddle