Develop Reference

How to return html code in a javascript function with conditional statements with select onchange

by selecting the option it has to return the html tags
<select onchange="getval(this);">
<option value="none" selected>none</option>
<option value="1">Blood Group</option>
<option value="2">Donor name</option>
</select>
<script>
function getval(sel)
{
if (sel == 1) {
return '<label for="Bloodgroup">Blood Group</label>
<select name="bg" class="form-control" id="exampleFormControlSelect1">
<option value="O+" selected>O+</option>
<option value="O-">O-</option>
<option value="A+">A+</option>
<option value="A-">A-</option>
</select>';
}else if (sel == 2) {
return ' <label for="name">Name</label>
<input type="text" name = "name" class="form-control" required>';
}
}
</script>
I want an output by choosing the options
for example: if the option is selected as bloodgroup
else if it is donor name

There's a couple of issues in your code. Firstly the argument you're passing to the getval() function is the select element reference, not the value which was selected, so the if condition needs to read the value property from the argument.
In addition your return statements in the function won't do anything alone, as nothing is done with the values you provide back from the function. To add the HTML in the strings to the DOM you need to call a function or property of a target element to append the content to. In the following example that's done using querySelector and innerHTML respectively:
let content = document.querySelector('#content');
function getval(el) {
if (el.value == 1) {
content.innerHTML = `<label for="Bloodgroup">Blood Group</label>
<select name="bg" class="form-control" id="exampleFormControlSelect1">
<option value="O+" selected>O+</option>
<option value="O-">O-</option>
<option value="A+">A+</option>
<option value="A-">A-</option>
</select>`;
} else if (el.value == 2) {
content.innerHTML = `<label for="name">Name</label>
<input type="text" name = "name" class="form-control" required>`;
}
}
<select onchange="getval(this);">
<option value="none" selected>none</option>
<option value="1">Blood Group</option>
<option value="2">Donor name</option>
</select>
<div id="content"></div>
However it's also worth noting that using inline event handlers in onclick attributes is no longer good practice. In addition, storing HTML within your JS should be avoided. A more modern solution would be to use an unobtrusive event handler and have all the HTML within the DOM when the page loads and simply toggle its visibility.
As you've tagged the question with jQuery, here's an example of how to do that:
let content = $('#content');
$('select').on('change', e => {
$('.toggle').hide().filter(`.${e.target.value}`).show();
});
.toggle { display: none; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select>
<option value="none" selected>none</option>
<option value="bloodgroup">Blood Group</option>
<option value="donor">Donor name</option>
</select>
<div id="content">
<div class="toggle bloodgroup">
<label for="Bloodgroup">Blood Group</label>
<select name="bg" class="form-control" id="exampleFormControlSelect1">
<option value="O+" selected>O+</option>
<option value="O-">O-</option>
<option value="A+">A+</option>
<option value="A-">A-</option>
</select>
</div>
<div class="toggle donor">
<label for="name">Name</label>
<input type="text" name = "name" class="form-control" required>
</div>
</div>

Open Another Input Text when the user selects an option

I am a newbie and I have this project where the user should have the option of custom input if the listed options are not in dropdown.
HTML
<div class="form-group">
<label class="col-sm-2 col-form-label">Select Page Size</label>
<select name = 'pageSelector' class="col-sm-3">
<option value ="">Select Page Size</option>
<option value ="84.1|118.9">A0</option>
<option value = "59.4|84.1">A1</option>
<option value = "7.4|10.5">A7</option>
<option value = "custom">Select Custom</option>
</select>
</div>
PHP
if(isset($_POST["pageSelector"]))
{
$result = $_POST['pageSelector'];
if($result == "")
{
echo "<script>alert('Please select the Page')</script>";
}
$result_explode = explode('|', $result);
$width_page = $result_explode[0];
$height_page = $result_explode[1];
// Converting the string variables to integer
$width_plate=(double)$width_plate;
$height_plate=(double)$height_plate;
$width_page=(double)$width_page;
$height_page=(double)$height_page;
// To calculate the number of pages that can be print with one selected plate
$calculated_width = $width_plate/$width_page;
$calculated_height = $height_plate/$height_page;
$print_include = (int)$calculated_height*(int)$calculated_width;
echo "<div class='h1'>Number of Prints in one plate ".$print_include." prints</div> ";
}
I would like if the user selects the custom option then a input text should appear on the screen.

If user selected a custom option then you can give him an input.
let selectEl = document.getElementById('select-list');
selectEl.addEventListener('change', (e) => {
if (e.target.value == 'custom') {
document.getElementById('txt-custom').style.display = 'block';
} else {
document.getElementById('txt-custom').style.display = 'none';
}
});
#txt-custom {
display: none;
}
<select id="select-list">
<option value="">Select an option</option>
<option value="1">Option 1</option>
<option value="2">Option 2</option>
<option value="custom">Custom</option>
</select>
<input type="text" id="txt-custom" name="custom-value" />

var pageSelector = document.getElementById('pageSelector');
var customInput = document.getElementById('customInput');
pageSelector.addEventListener('change', function(){
if(this.value == "custom") {
customInput.classList.remove('hide');
} else {
customInput.classList.add('hide');
}
})
.hide {
width: 0;
height: 0;
opacity: 0;
}
<div class="form-group">
<label class="col-sm-2 col-form-label">Select Page Size</label>
<select name = 'pageSelector' class="col-sm-3 page" id="pageSelector">
<option value ="">Select Page Size</option>
<option value ="84.1|118.9">A0</option>
<option value = "59.4|84.1">A1</option>
<option value = "7.4|10.5">A7</option>
<option value = "custom">Select Custom</option>
</select>
<input type="text" class="hide" placeholder="Custom Selector" name="custom" id="customInput">
</div>

Demo Code :
First you should have input with style="display:none" and with jQuery
jQuery(document).ready(function() {
jQuery("#selectId").change(function() {
if (jQuery(this).val() === 'custom'){
jQuery('input[name=other_input]').show();
} else {
jQuery('input[name=other_input]').hide();
}
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<select name = 'pageSelector' class="col-sm-3" id="selectId" >
<option value ="">Select Page Size</option>
<option value ="84.1|118.9">A0</option>
<option value = "59.4|84.1">A1</option>
<option value = "7.4|10.5">A7</option>
<option value = "custom">Select Custom</option>
</select>
<br><br><br>
<input type="text" name="other_input" style="display:none" />

Angular Version
Angular CLI: 13.0.3
Node: 16.15.0
Package Manager: npm 8.5.5
In .html File
**<div class="col-md-6">
<label class="form-label">Attendence Type</label>
<select (change)="type($event)" class="form-select" aria-label="Default select example" >
<option selected value="P">Present</option>
<option value="A">Absent</option>
<option value="PL">Paid Leave</option>
<option value="UL">Unpaid Leave</option>
</select>
</div>**
I want to Show this input after select paid leave
**<div *ngIf="plFlag" class="col-md-6">
<label class="form-label">Leave Type</label>
<select class="form-select" aria-label="Default select example">
<option selected disabled>Leave Type</option>
<option value="CL">Causel Leave</option>
<option value="SL">Seek Leave</option>
</select>
</div>**
and in .ts File
**type(event: any) {
console.log(event.target.value);
if (event.target.value == "PL") {
this.plFlag = true;
}
else {
this.plFlag = false;
}
}**

page is still reloading with event.preventDefault();

if the select drop-down menu has value of NULL, it should stop the page from loading. The jQuery works alerting the user of the issue, however the page still continues to the next page. Any assistance would be superb. Thanks
Luke
<fieldset class="form-group">
<label for="question-1">1. What age group are you?</label> <br>
<select class="drop-down" id = "ageChoice">
<option value="">Please Select</option>
<option value="16minus">16 or below</option>
<option value="16-18">16 to 18</option>
<option value="19-25">19 to 25</option>
<option value="26-34">26 to 34</option>
<option value="35-42">35 to 42</option>
<option value="43-50">43 to 50</option>
<option value="51-60">51 to 60</option>
<option value="61plus">61+</option>
</select>
</fieldset>
<input class="btn btn-primary" type="button" id= "next" value="Next" onClick="location.href='first-test.html' ">
$("#next").click(function () {
var age = $('#ageChoice');
if (age.val() === '') {
event.preventDefault();
alert("Please select your age group, thank you.");
}
else
return;
});

Ok, so because you have two click handlers, the event is being processed twice. The 'Default' you are trying to prevent is not the onClick="location.href='first-test.html' . That is being processed after your jQuery click function. So we take the onClick out of the html. and add the functionality to the jQuery click event (we could do it either way, but becuase you already have most of the code set up already we'll do it this way)
Here is the reworked code:
<fieldset class="form-group">
<label for="question-1">1. What age group are you?</label> <br>
<select class="drop-down" id = "ageChoice">
<option value="">Please Select</option>
<option value="16minus">16 or below</option>
<option value="16-18">16 to 18</option>
<option value="19-25">19 to 25</option>
<option value="26-34">26 to 34</option>
<option value="35-42">35 to 42</option>
<option value="43-50">43 to 50</option>
<option value="51-60">51 to 60</option>
<option value="61plus">61+</option>
</select>
</fieldset>
<input class="btn btn-primary" type="button" id= "next" value="Next">
and the jquery:
$("#next").on('click', function (event) {
var age = $('#ageChoice');
if (age.val() === '') {
alert("Please select your age group, thank you.");
} else {
location.href='first-test.html'
}
});

How to use if else statements in select form?

In my registration page, I'm gonna use two drop-down select that one of them should be hidden if its Negative and if its positive new drop-down will open to choose ...
In mysql table I've table as diabetes name with enom
enum('negative', 'insulin', 'drug', 'ndm', 'mody', '')
Here's my code:
<div><label for="diabetes">Diabetes:</label>
<select id="diabetes" name="diabetes">
<option value="negative">Negative</option>
<option value="">Positive</option>
</select>
</div>
<div><label for="diabetestype">Diabetes Type:</label>
<select id="diabetestype" name="diabetestype">
<option value="insulin">Insulin</option>
<option value="drug">Drug</option>
<option value="ndm">NDM</option>
<option value="mody">MODY</option>
</select>
</div>
For example: If Diabetes is negative value is negative as default then Diabetes Type is hidden
and
If Diabetes is positive then Diabetes type will be appeared to choose items.
those values like insulin, drug, mdm, mody should be inserted into this:
value="positive"
How can I make it through java script?
I can't add class or div or span. Is it possible just through JavaScript using ??
Thank you so much

Use jquery, it is comparatively easier.
$(document).ready(function(){
$("#diabetestype").hide();
$("#diabetes").on("change", function(){
var v = $(this).val();
if(v=="positive"){
$("#diabetestype").show();
}else{
$("#diabetestype").hide();
}
});
});
To make this code workable, you need to add value of Positive option also. So instead value="" change it to value="positive".
You can even hide the label also:
$(document).ready(function(){
$("#diabetestype").closest("div").hide();
$("#diabetes").on("change", function(){
var v = $(this).val();
if(v=="positive"){
$("#diabetestype").closest("div").show();
}else{
$("#diabetestype").closest("div").hide();
}
});
});

<div><label for="diabetes">Diabetes:</label>
<select id="diabet" name="diabet" onchange="checkDiabet();">
<option value="negative">Negative</option>
<option value="positive" id="isDiabet">Positive</option>
</select>
</div>
<div id="type" style="display: hidden;">
<label for="diabetestype">Diabetes Type:</label>
<select id="diabetestype" name="diabetestype">
<option value="insulin">Insulin</option>
<option value="drug">Drug</option>
<option value="ndm">NDM</option>
<option value="mody">MODY</option>
</select>
</div>
<script>
function checkDiabet() {
var isDiabet = document.getElementById("isDiabet").selected;
if (isDiabet == true) { document.getElementById("type").removeAttribute("style"); }
else { document.getElementById("type").style.display = "none"; }
}
</script>
First, set the first select to fire the function checkDiabet() by the attribute onchange. Then give the option an id, which needs to be checked, so you can access it easily.
Then, set the second select to display: none This could be done in a CSS header or file, or like in this case inline. (div style=""), also add an id to access it easily. (div id="type")
Now comes the function checkDiabete(). It checks if the select is selected (can be true or false (bool)). Is selected => show (div id="type"), if not, hide this div (and all of it's contents)
(if is already hidden, it then overwrites the (style="display: none;") with (style="display: none;))
That's it! :)

Try this:
function SelectDiabetes() {
var d = document.getElementById("diabetes").value;
var dType = document.getElementById("diabetestypebox");
if(d == "negative")
dType.style.display = "none";
else
dType.style.display = "block";
}
SelectDiabetes();
<div><label for="diabetes">Diabetes:</label>
<select id="diabetes" name="diabetes" onchange="SelectDiabetes(this.value);">
<option value="negative">Negative</option>
<option value="positive">Positive</option>
</select>
</div>
<div id="diabetestypebox"><label for="diabetestype">Diabetes Type:</label>
<select id="diabetestype" name="diabetestype">
<option value="insulin">Insulin</option>
<option value="drug">Drug</option>
<option value="ndm">NDM</option>
<option value="mody">MODY</option>
</select>
</div>

Call a js function onchange of select id diabetes
<div><label for="diabetes">Diabetes:</label>
<select id="diabetes" name="diabetes" onchange="toggleTypes()">
<option value="negative">Negative</option>
<option value="">Positive</option>
</select>
</div>
<div><label for="diabetestype">Diabetes Type:</label>
<select id="diabetestype" style="display:none" name="diabetestype">
<option value="insulin">Insulin</option>
<option value="drug">Drug</option>
<option value="ndm">NDM</option>
<option value="mody">MODY</option>
</select>
</div>
Use the following javascript
function toggleTypes(){
var el=document.getElementById('diabetes');
var medElem=document.getElementById('diabetestype');
if(el.value=='positive') {
medElem.style.display='block';
} else {
medElem.style.display='none';
}
}

Drop down text input option

I want a drop down element where user can select from available options or select enter value option which in turn allows to enter value.
I specifically want that user can enter value only when they select "Enter a value " option.
Here is what I have tried so far.
HTML-
<div class="ginput_container">
<select name="input_4" id="input_1_4" class="medium gfield_select" tabindex="15">
<option value="0">None</option>
<option value="155">1-70</option>
<option value="185">71-250</option>
<option value="*">Enter value</option>
</select>
<input type="text" value="None" class="holder" >
</div>
JavaScript-
jQuery(".gfield_select").change(function() {
var val = jQuery(this).val();
var enter = jQuery(this).parent().find('option:selected').text();
var x = jQuery(this).parent();
if (enter ==="Enter a value" || enter === "Enter value"){
var holder = x.find('.holder');
holder.val('');
holder.prop('disabled',false);
holder.focus();
} else {
x.find('.holder').val(x.find('option:selected').text());
}
});
JS fiddle
however it wont work properly if i click the enter value option again.

I think there are many plugins that do what you want but if you want to create your own, it's a basic and simple solution.
You can create a select and a textbox with display:none like this:
<select id="ddlDropDownList">
<option value="1">Item 1</option>
<option value="2">Item 2</option>
<option value="3">Item 3</option>
<option value="-1">Enter Value</option>
</select>
<input id="txtTextBox" type="text" />
<style>
#txtTextBox{
display:none;
}
</style>
then try this JQuery:
$("#ddlDropDownList").change(function(){
if($(this).val() == '-1'){
$("#txtTextBox").fadeIn();
}else{
$("#txtTextBox").fadeOut();
}
});
Check JSFiddle Demo

I have forked your JSFiddle to http://jsfiddle.net/pwdst/4ymtmf7b/1/ which I hope does what you wanted to achieve.
HTML-
<div class="ginput_container">
<label for="input_1_4">Select option</label>
<select class="medium gfield_select" id="input_1_4" name="input_4" tabindex="15">
<option value="0">None</option>
<option value="155">1-70</option>
<option value="185">71-250</option>
<option value="*">Enter value</option>
</select>
<div>
<label class="hidden-label" for="input_1_4_other">Other value</label>
<input class="holder" id="input_1_4_other" disabled="disabled" name="input_1_4_other" placeholder="None" type="text" />
</div>
</div>
JavaScript-
jQuery(".gfield_select").change(function() {
var $this = jQuery(this);
var val = $this.val();
var holder = $this.parent().find('.holder');
if (val === "*"){
holder.val('');
holder.removeAttr('disabled');
holder.focus();
} else {
holder.val(this.options[this.selectedIndex].text);
holder.attr('disabled', 'disabled');
}
});
When the "Enter value" option is chosen then the input box is enabled, value set to an empty string, and it is focused. If another option is chosen then the text input is disabled again, and the text value from the select list is used.

Thanks guys
I guess i have found my answer
HTML-
<div class="ginput_container">
<select name="input_4" id="input_1_4" class="medium gfield_select" tabindex="15">
<option value="0">None</option>
<option value="155">1-70</option>
<option value="185">71-250</option>
<option value="*">Enter value</option>
</select>
<input type="text" value="None" class="holder" >
</div>
JavaScript-
jQuery(".gfield_select").change(function() {
var val = jQuery(this).val();
var enter = jQuery(this).parent().find('option:selected').text();
var x = jQuery(this).parent();
if (enter ==="Enter a value" || enter === "Enter value"){
var holder = x.find('.holder');
holder.val('');
holder.prop('disabled',false);
holder.focus();
jQuery(this).val("0"); // Change select value to None.
} else {
x.find('.holder').val(x.find('option:selected').text());
x.find('.holder').prop('disabled',true);
}
});
JS FIDDLE