Develop Reference

Toggle html button depending if textarea is filled or empty

Hey the task i try to achieve is to activate and deactivate a button depending on, if there is text in a textarea or not.
Here the code I'm trying to get going.
var button = document.getElementById("button_01");
var textarea = document.getElementById("textarea_01");
$(button).prop('disabled', true);
textarea.addEventListener('keyup', function() {
button.disabled = !this.value;
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="div_01">
<h1>String Editor</h1>
<textarea id="textarea_01" rows="5" placeholder="Paste your string here"></textarea>
</div>
<div id="div_02">
<h1>Options</h1>
<button id="button_01" type="button" value="submit">
Modify
</button>
</div>
and here a fiddle: Fiddle
What I'm really not understanding here is, why the button which I disabled in the js part is still active
I'm an absolute html/js/web developement newbie, so please give some explanation.
Thanks in advance

The jsFiddle doesn't work because there's no jQuery CDN link.
You can find an updated version, witch includes the jQuery CDN here.
You're using jQuery to disable the button on page-load.
I'll recommend using HTML for that:
<button id="button_01" type="button" value="submit" disabled>
Then, your code appears to work just fine because there's no jQuery needed anymore:
var button = document.getElementById("button_01");
var textarea = document.getElementById("textarea_01");
textarea.addEventListener('input', function() {
button.disabled = !this.value;
});
<div id="div_01">
<h1>String Editor</h1>
<textarea id="textarea_01" rows="5" placeholder="Paste your string here"></textarea>
</div>
<div id="div_02">
<h1>Options</h1>
<button id="button_01" type="button" value="submit" disabled>
Modify
</button>
</div>
Note;
Changed event from keyup to input so things like right-click and paste will trigger the event. (Thx to #freedomn-m)

Try like this.
var button = document.getElementById("button_01");
var textarea = document.getElementById("textarea_01");
button.disabled = true;
textarea.addEventListener('keyup', function() {
button.disabled = !this.value;
});
<div id="div_01">
<h1>String Editor</h1>
<textarea id="textarea_01" rows="5" placeholder="Paste your string here"></textarea>
</div>
<div id="div_02">
<h1>Options</h1>
<button id="button_01" type="button" value="submit">
Modify
</button>
</div>

Problem on Passing getElementById value to textbox Value

I can see the scanned value (id="code") on p element. How can I fill the textbox with this value?
Actually when I press the Scan Barcode button, camera is open and scan an EAN13 barcode, and the value is shown in P element (590123... is the barcode). Can be seen below. But I want to see this value in textbox.
function barcode() {
var resultElement = document.getElementById("code");
// setupLiveReader(resultElement)
}
<p id="code">code is appearing here</p>
<input class="form-control" type="text" id="code">
<button onclick="barcode()" type="submit" class="btn btn-primary btn-sm">Scan Barcode</button>

You can't have two elements with the same id. To get the content of the p tag just call innerHTML on it. After that set the value of your input with the new id.
<p id="code">code is appear here</p>
<input class="form-control" type="text" id="codeInput">
<button onclick="barcode()" type="submit" class="btn btn-primary btn-sm">Scan Barcode</button>
<script>
function barcode() {
var resultElement = document.getElementById("code").innerHTML;
//setupLiveReader(resultElement)
document.getElementById("codeInput").value = resultElement;
}
</script>

Change the id so that you only have one id="code", then update the script so resultElement has the id of the <input...
<p id="code">code is appear here</p>
<input class="form-control" type="text" id="code-input">
<button onclick="barcode()" type="submit" class="btn btn-primary btn-sm">Scan Barcode</button>
<script>
function barcode() {
const resultElement = document.getElementById("code-input");
setupLiveReader(resultElement);
}
</script>

function getValue() {
var resultInputValue = document.getElementById("inputValue").value;
document.getElementById("valueShow").innerHTML = resultInputValue;
}
<p id="valueShow">input value is appear here</p>
<input type="text" id="inputValue">
<button onclick="getValue()" type="submit">Get Value</button>

html validation on button or hidden filed

wondering if anyone can help. As part of a form, i'm using a selection of buttons to capture satisfaction, rather than radio or dropdown. I'm using a jquery to capture the value of the button and adding it to a hidden field - the field the form is using to submit the information.
All works fine, however, i want to put validation, to make sure an answer is captured - but HTLM5 validation does not support buttons or hidden fields. Is there a was i can use JS to check if a button has been pressed on submit, and if not, toggle the html validator for that field?
Here the code i have so far;
<div class="form-group">
<label class="control-label required input_satisfaction" for="feedbackQuestions[56]">Please rate the venue facilities: <span class="required ">*</span></label>
<input required="required" type="hidden" name="feedbackQuestions[56]" id="feedbackQuestions_56">
<div id="feedbackQuestions_56_group" class="row">
<div class="col-xs-3"><button class="satisfactionBtn btn btn-primary btn-lg btn-block" required="required" name="Questions[56][0]" value="Excellent">Excellent</button></div>
<div class="col-xs-3"><button class="satisfactionBtn btn btn-primary btn-lg btn-block" required="required" name="Questions[56][1]" value="Good">Good</button></div>
<div class="col-xs-3"><button class="satisfactionBtn btn btn-primary btn-lg btn-block" required="required" name="Questions[56][2]" value="Satisfactory">Satisfactory</button></div>
<div class="col-xs-3"><button class="satisfactionBtn btn btn-primary btn-lg btn-block" required="required" name="Questions[56][3]" value="Poor">Poor</button></div>
</div>
<script>
$('#feedbackQuestions_56_group .satisfactionBtn').click(function (e) {
e.preventDefault();
$('#feedbackQuestions_56_group .satisfactionBtn').each(function( index ) {
$( this ).removeClass('active');
});
var thisval = $(this).val();
$('#feedbackQuestions_56').val(thisval);
$(this).addClass('active');
});
</script>
</div>
I know i need to add a trigger to the submit button futher down the page, so i can do a jquery .click() and then prevent the event until i've checked, but not sure how to actually check or how to trigger the validation.

I would actually store it as a global JS variable rather than a hidden field. you can reparse this value to the hidden field through jQuery if you want, but I don't see a use in that. Also divs are selectable in JS as well, so you do not need them to be just one or the other.
var isSelected = false;
$('#feedbackQuestions_56_group .satisfactionBtn').click(function (e) {
e.preventDefault();
$('#feedbackQuestions_56_group .satisfactionBtn').each(function (index) {
$(this).removeClass('active');
});
var thisval = this.id;
console.log("thisval: " + thisval);
$('#feedbackQuestions_56').val(thisval);
$(this).addClass('active');
isSelected = true
});
$('#onSubmit').click(function () {
console.log(isSelected);
//
// Look into ajax post command
//
if (isSelected == true) {
// ajax call here
}
else {
alert("Please select a rating")
}
})
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<div class="form-group">
<label class="control-label required input_satisfaction" for="feedbackQuestions[56]">Please rate the venue facilities:
<span class="required ">*</span>
</label>
<div id="feedbackQuestions_56_group" class="row">
<div class="col-xs-3 satisfactionBtn btn btn-primary btn-lg btn-block" name="Questions[56][0]" id="Excellent">Excellent
</div>
<div class="col-xs-3 satisfactionBtn btn btn-primary btn-lg btn-block" name="Questions[56][1]" id="Good">Good
</div>
<div class="col-xs-3 satisfactionBtn btn btn-primary btn-lg btn-block" name="Questions[56][2]" id="Satisfactory">Satisfactory
</div>
<div class="col-xs-3 satisfactionBtn btn btn-primary btn-lg btn-block" name="Questions[56][3]" id="Poor">Poor
</div>
<div class=" btn btn-primary btn-lg btn-block" id="onSubmit">Submit</div>
</div>

Since that hidden field value is filled by code not user, code should validate the value(or no need to validate).
It sounds really strange that the hidden field need to be validated.
Edited
If you really need to validate hidden field, the original way is not working, but you can do it tricky by just add opacity:0 style.
Add such style make it invisible but not hidden, so the validate should work fine as usual.
But just remember you must change the type="hidden" to type="text"

How to clear textarea field onclick in AJAX?

How to clear textarea field onclick? the problem is I am using AJAX. it won't reload the page. can anyone help me to solve this problem.
<div class="write_comment" style="">
<textarea type="text" id="form_task_comment" name="form_task_comment" value="" placeholder="Write your comment here..."></textarea>
<div class="buttons" style="float:right">
<button id="btn_comment_submit" class="btn btn-default btn hoverable btn-sm btn_comment_submit" style="margin:0rem;" type="submit">Add Comment</button>
</div>
</div>

Try this. Click on button to clear Textarea
$('.clearText').click(function(){
$("#form_task_comment").val('');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class="clearText">Click Here To Clear Textarea</button>
<br>
<textarea id="form_task_comment">This is textarea</textarea>

In case you do not want to use jQuery. And the other posts above do not mention how to reset your textarea ON send. When you bind onclick, it would clear the text BEFORE sending. Therefore you need to use form onsubmit
var textArea = document.getElementById("form_task_comment")
var form = document.getElementById("form-name")
form.addEventListener("submit", function(event) {
textArea.value = "";
event.preventDefault();
}, false)
<div class="write_comment" style="">
<form id="form-name" >
<textarea type="text" id="form_task_comment" name="form_task_comment" value="" placeholder="Write your comment here..."></textarea>
<div class="buttons" style="float:right">
<button id="btn_comment_submit" class="btn btn-default btn hoverable btn-sm btn_comment_submit" style="margin:0rem;" type="submit">Add Comment</button>
</div>
</form>
</div>

Simply just replace textarea.value with nothing when button is clicked??
html code:
<input type="button" value="Clear Text" onclick="eraseText();"></input>
Javascript:
function eraseText()
{
document.getElementById("form_task_comment").value = "";
}

You can simply clear the value of text area using .val() like this
$("#form_task_comment").val('');
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea id="form_task_comment">This is textarea</textarea>
Add this line of code wherever you want to clear the text area

Getting value of a particular element within a particular div using jQuery

In the markup, i have several divs with same id and inside those divs there are paragraphs and buttons. Now when a button is clicked, i want to get the value of a corresponding paragraph tag under the same div as that particular button. How can i do this with jQuery? The markup is as followed:
<div class="col-sm-5 narrow">
<p id="title">Jhon123</p>
<p id="text">This is the status of jhon</p>
<p>posted at 12:30pm GMT6+</p>
<form class="form-inline">
<input type="text" class="form-control" id="reply" placeholder="Type and enter to reply">
<button type="button" class="btn btn-default" id="repost">Re-Tweet</button>
</form>
</div>
When the button with the id #repost is clicked, i want to access the html inside the p tag with the id #text. I tried something like this:
$('#retweet').click(function(e){
e.stopPropagation();
var text = $(this).parent("div").closest('#text');
alert("some retweet button has been pressed which has the text:"+text);
});

You can use the jQuery .closest() function to get the containing <div> and then find the <p> tag you want inside it:
$('#repost').on('click', function () {
var text = $(this).closest('div[class^=col]').find('#text').html();
console.log(text);
});
The div[class^=col] selector means "find the closest div tag with a class starting with col". This allows you to use the other bootstrap column classes as well and have it still work.

$('#repost').click(function(){
console.log($(this).closest('div').find('#text').html());
});
See demo http://jsbin.com/wojupoyosa/1/edit?html,js,console,output
and as comments suggest you IDs should be unique per page so you should use a class or something else instead.

$( "#text" ).text() will give you the value inside P tag. So your code will look something like:
$('#repost').click(function(){
$( "#text" ).text() // save it to wherever you want
});

As a side note it is generally frowned upon to have css id's that are not unique - shared identifiers should use a class.

If you change all your ids into classes as shown in the demo below, then the following code should work fine. Also, you do not need the form element.
$('.repost').click(function(){
var text = $(this).closest('div').find('.text').text();
alert("some retweet button has been pressed which has the text: " + text);
});
$(function() {
$('.repost').click(function(){
var text = $(this).closest('div').find('.text').text();
alert("some retweet button has been pressed which has the text: " + text);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div class="col-sm-5 narrow">
<p class="title">Jhon123</p>
<p class="text">This is the status of jhon</p>
<p>posted at 12:30pm GMT6+</p>
<form class="form-inline">
<input type="text" class="form-control reply" placeholder="Type and enter to reply">
<button type="button" class="btn btn-default repost">Re-Tweet</button>
</form>
</div>
<div class="col-sm-5 narrow">
<p class="title">Mary123</p>
<p class="text">This is the status of mary</p>
<p>posted at 12:35pm GMT6+</p>
<form class="form-inline">
<input type="text" class="form-control reply" placeholder="Type and enter to reply">
<button type="button" class="btn btn-default repost">Re-Tweet</button>
</form>
</div>