Develop Reference

Change a select option thanks to another option

What I'm trying is something pretty basic, but I can't do it because the examples I see aren't anything similar to what I'm looking for.
There are 2 select, one of them you choose manually and the other dynamically changes depending on the value of the first one.
If the value of the first select is 1, that in the second one they only appear whose value is 1 as well.
I want to make it 100% JavaScript, I don't want any JQuery.
HTML.php
<select onchange="catch_value_types()" name="types" id="types">
<option value="1">Meat</option>
<option value="2">Fish</option>
<option value="3">Vegetables</option>
</select>
<select name="food" id="food">
<option value="1">Pork</option>
<option value="1">Cow</option>
<option value="1">Chicken</option>
<option value="2">Sardine</option>
<option value="2">Salmon</option>
<option value="2">Mackerel</option>
<option value="3">Spinach</option>
<option value="3">Kale</option>
<option value="3">Green peas</option>
</select>
JavaScript.js
function catch_value_types() {
var types_value_option = document.getElementById("types").value;
// What should I put here?
}

Loop through the options and hide if value doesnot match
function catch_value_types() {
const selectedValue = document.getElementById("types").value;
const select2 = document.getElementById("food");
Array.from(select2.options).forEach((node) => node.style.display = node.value === selectedValue ? "block": "none");
}
<select onchange="catch_value_types()" name="types" id="types">
<option value="1">Meat</option>
<option value="2">Fish</option>
<option value="3">Vegetables</option>
</select>
<select name="food" id="food">
<option>Please Select</option>
<option value="1">Pork</option>
<option value="1">Cow</option>
<option value="1">Chicken</option>
<option value="2">Sardine</option>
<option value="2">Salmon</option>
<option value="2">Mackerel</option>
<option value="3">Spinach</option>
<option value="3">Kale</option>
<option value="3">Green peas</option>
</select>

Disable 3th, 4th dropdown list if 1st or 2nr are selected

I have this issue: In my form there are 4 dropdownlist and when the 1st (category1) or 2nd (software1) dropdown list is selected, the 3th (category2) and 4th (software2) must be disabled.
For this issue I find this script at disable-second-dropdown-if-the-first-is-not-selected but I do not trust to modify this:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
category1
<select name='cat1'>
<option value='0'>Select one</option>
<option value='1'>little</option>
<option value='2'>good</option>
</select>
software1
<select name='soft1'>
<option value=''>Select one</option>
<option value='W'>Word</option>
<option value='E'>Excel</option>
<option value='PP'>Power Point</option>
</select>
<br />
category2
<select name='cat2'>
<option value='0'>Select one</option>
<option value='1'>little</option>
<option value='2'>good</option>
</select>
software2
<select name='soft2'>
<option value=''>Select one</option>
<option value='W'>Word</option>
<option value='E'>Excel</option>
<option value='PP'>Power Point</option>
</select>
<script type="text/javascript">
var setEnabled = function(e) {
var name = this.name.replace(/1/, '2'); //get name for second drop down
$('select[name=' + name + ']')
.prop('disabled', 0 === this.selectedIndex) // disable if selected option is first one
};
$(function() {
$('select[name=cat1], select[name=soft1]')
.on('change', setEnabled)
.trigger('change'); // trigger on page load
});
</script>
How to modify this?
Thanks

I think the main thing you want is to flip === for !==
However, to get this working on a matrix, where both top inputs trigger enabling/disabling of both bottom inputs, you'll need to test both on change of either.
var setEnabled = function(e) {
var selected = $('select[name=cat1]').prop('selectedIndex') > 0 || $('select[name=soft1]').prop('selectedIndex') > 0;
$('select[name=cat2], select[name=soft2]').prop('disabled', selected); // disable if selected option is first one
if (selected) {
$('select[name=cat2], select[name=soft2]').prop('selectedIndex', 0)
}
};
$(function() {
$('select[name=cat1], select[name=soft1]')
.on('change', setEnabled)
.trigger('change'); // trigger on page load
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
</script>
category1
<select name='cat1'>
<option value='0'>Select one</option>
<option value='1'>little</option>
<option value='2'>good</option>
</select>
software1
<select name='soft1'>
<option value=''>Select one</option>
<option value='W'>Word</option>
<option value='E'>Excel</option>
<option value='PP'>Power Point</option>
</select>
<br />
category2
<select name='cat2'>
<option value='0'>Select one</option>
<option value='1'>little</option>
<option value='2'>good</option>
</select>
software2
<select name='soft2'>
<option value=''>Select one</option>
<option value='W'>Word</option>
<option value='E'>Excel</option>
<option value='PP'>Power Point</option>
</select>

Show a second select box based on the option chosen in the first?

I have the following select drop down box:
<select name="selectcourier" required>
<option value="">Please Select</option>
<option value="collection">Collection</option>
<option value="Interlink">Interlink</option>
<option value="DespatchBay">Despatch Bay</option>
<option value="International">International</option>
</select>
What I want to do is if Interlink is selected a secondary select box appears below it and disappears if it unselected and another option is chosen instead. This is the second select drop down box.
<label>Select Shipping Courier:</label>
<select name="selectcourier" required>
<option value="1">Please Select</option>
<option value="2">Next Day</option>
<option value="3">2-3 Day</option>
<option value="3">Pre 12</option>
</select>
How can I go about getting this working?

bind an event with javascript on change and insert a new element in the DOM (the second select statement) like:
(provided you have jquery)
var secondSelect="your_html_here";
$("name='selectcourier'").change(function() {
if (this.val()=='Interlink') {
$('body').append(secondSelect); }
else {
$('#secondselectid').remove();
});
customise the html and where you want to append the second select

<script>
$(function(){
$('#s1').hide();
});
function call()
{
var check=$('#s2').val();
if(check=="Interlink")
{
$('#s1').show();
}
else
{
$('#s1').hide();
}
}
</script>
<select name="selectcourier" required onchange="call();" id="s2" >
<option value="">Please Select</option>
<option value="collection">Collection</option>
<option value="Interlink">Interlink</option>
<option value="DespatchBay">Despatch Bay</option>
<option value="International">International</option>
</select>
<label>Select Shipping Courier:</label>
<select name="selectcourier" required id="s1">
<option value="1">Please Select</option>
<option value="2">Next Day</option>
<option value="3">2-3 Day</option>
<option value="3">Pre 12</option>
</select>
You can use the above code to achieve your task

Just react on the event of changing the value of the first select.
If the value equals 'Interlink' display the second select - if the value is something else hide the second select.
<select name="selectcourier" required onchange="document.getElementById('interlink_addition').style.display = (this.value=='Interlink' ? 'block' : 'none')">
<option value="">Please Select</option>
<option value="collection">Collection</option>
<option value="Interlink">Interlink</option>
<option value="DespatchBay">Despatch Bay</option>
<option value="International">International</option>
</select>
<div id="interlink_addition" style="display:none">
<label>Select Shipping Courier:</label>
<select name="selectcourier" required>
<option value="1">Please Select</option>
<option value="2">Next Day</option>
<option value="3">2-3 Day</option>
<option value="3">Pre 12</option>
</select>
</div>

you can use ajax for this. write a ajax function to show second select box and call it on onChange event of the first select Box

How to dynamically add options to a select menu using a prompt to get the value

I have a select menu drop down list
<div data-role="fieldcontain" data-controltype="selectmenu">
<select id="selectmenu4" name="">
<option value="option1">
Category:
</option>
<option value="rent">
Rent
</option>
<option value="restaurant">
Restaurant
</option>
<option value="drinks">
Drinks
</option>
<option value="power">
Power
</option>
<option value="water">
Water Supply
</option>
<option value="specifyValue">
Other
</option>
<option value="gas">
Gas
</option>
<option value="pharmacy">
Pharmacy
</option>
<option value="coffeshop">
Coffeshop
</option>
<option value="groceries">
Groceries
</option>
<option value="gym">
Gym
</option>
<option value="clothes">
Clothes/Shoes/Accessories
</option>
<option value="vet">
Vet
</option>
<option value="pet_sup">
Pet supplies
</option>
<option value="other">Other</option>
</select>
</div>
When option other is selected by the user I want a prompt to pop out and I want the value of the input to be stored as a new option in the select menu.
This is the function I am using for the prompt:
var addAnotherOption = function(){
var newCat = function(){
if(document.getElementById("selectmenu4").value === "other"){
return (prompt("Define new Category"));
}document.getElementById("selectmenu4")createElement(newCat);}

Can you try this code, Do you want something similar?
$(function(){
$("#selectmenu4").change(function(){
var DropdownValue =$(this).val();
if(DropdownValue=='other'){
var OtherData=prompt("Enter Other values!","");
if(OtherData){
$("#selectmenu4").append("<option value="+OtherData+" >"+OtherData+"</option>");
}
}
});
});

Try this code you must include JQuery in your file
$(document).ready(function(){
$("#selectmenu4").change(function(){
var SelectValue =$(this).val();
if(SelectValue=='other')
{
var OtherData=prompt("Enter Other values!","");
if(OtherData)
{
$("#selectmenu4").append("<option value="+OtherData+">"+OtherData+"</option>");
}
}
});
});
Check Fiddle

On select loading options in a select box

I have a main drop down list which contains state names, when i select each state name i need to display the city names in a select box, but the select box name should be same because when i give different select box with same name the data is not storing in sql database. so i need to load the specific city names on each state select. any option
<option value="">Select your Location</option>
<option value="CHENNAI">CHENNAI</option>
<option value="GURGAON">GURGAON</option>
</select>
<select name="site">
<option value=""> Select Site </option>
<option value="City1"> City1</option>
<option value="City2"> City2</option>
<option value="City3"> City3</option>
<option value="City3"> City3</option>
</select>
<select name="site">
<option value=""> Select Site </option>
<option value="City1"> City1</option>
</select>

Demo
You can use prop('disabled', true / false); to manage which city to choose. You should not have 2 selects with same name, so because you need them in sql I made a fix for it. Notice also in your post you miss first <select> and "City 3" comes up 2 times.
html
<select name="state" id="sel_state">
<option value="">Select your Location</option>
<option value="CHENNAI">CHENNAI</option>
<option value="GURGAON">GURGAON</option>
</select>
<select name="site" id="CHENNAI">
<option value="">Select Site</option>
<option value="City1">City1</option>
<option value="City2">City2</option>
<option value="City3">City3</option>
<option value="City4">City3</option>
</select>
<select name="site" id="GURGAON">
<option value="">Select Site</option>
<option value="City1">City1</option>
</select>
jQuery
$(function () {
$("#sel_state").change(function () {
var a = $("#sel_state option:selected").text();
if (a == 'CHENNAI') {
$('#GURGAON').prop('disabled', true);
$('#CHENNAI').prop('disabled', false);
$('#GURGAON').prop('name', 'site_ignored');
$('#CHENNAI').prop('name', 'site');
}
if (a == 'GURGAON') {
$('#CHENNAI').prop('disabled', true);
$('#GURGAON').prop('disabled', false);
$('#GURGAON').prop('name', 'site');
$('#CHENNAI').prop('name', 'site_ignored');
}
});
});