Develop Reference

How do I use jQuery to select an input for use with .empty()?

In the HTML below, how can I use jQuery .empty to remove <div class="password-link"> and everything inside - the href link, the text Log in and the </a> - as well as the closing </div>?
I'm trying to use
jQuery('#lostpasswordform input#wp-submit').empty('password-link');
but I must not be selecting the input or the form in the correct way.
<form name="lostpasswordform" id="lostpasswordform" action="http://localhost/~user/wp-core/wp-login.php?action=lostpassword" method="post">
<input type="hidden" name="redirect_to" value="">
<p class="submit">
<input type="submit" name="wp-submit" id="wp-submit" class="button button-primary button-large" value="">
// Remove this:
<div class="password-link">Log in</div>
</p>
</form>

Make sure you want to remove that element or clean the content of it
$('.password-link').empty() will return:
<div class="password-link"></div>
while $('.password-link').remove() will remove/delete that element .password-link

You can try this way
$('#lostpasswordform input#wp-submit').on("click", function(){
var $passwordlink = $(".password-link");
$passwordlink.empty();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form name="lostpasswordform" id="lostpasswordform" action="http://localhost/~user/wp-core/wp-login.php?action=lostpassword" method="post">
<input type="hidden" name="redirect_to" value="">
<p class="submit">
<input type="submit" name="wp-submit" id="wp-submit" class="button button-primary button-large" value="">
// Remove this:
<div class="password-link">Log in</div>
</p>
</form>

.empty() removes the child nodes and content. So the div you want to remove should be wrapped around another div and you can call the .empty() method on that parent div.

How to hide form submit button unless input is focussed (vanilla JS)

I have a form where I would like to hide the submit button unless the input is focussed/selected.
There is only one input apart from the submit.
I need to do this using pure JS (or perhaps CSS/Sass), not jQuery etc.
Basic example:
<form>
<input type="text" placeholder="Example field">
<input type="submit value="Submit">
</form>

First get references to your objects, so change the HTML for example :
<form>
<input id="input_1" type="text" placeholder="Example field">
<input id="submit" type="submit" value="Submit" />
</form>
With some CSS we will hide the submit by default:
#submit{
display:none;
}
We have added Id's, now we add the event listeners for focus on input..
document.getElementById("input_1").addEventListener('focus', function(){
document.getElementById("submit").style.display = 'block';
}
, true);
The second param into the eventListener will execute when the event is fired..
You will need to do more work on this..
https://jsfiddle.net/7uzkzr67/

Here is the pure CSS solution;
.showonfocus{
display:none;
}
.inputfield:focus + .showonfocus{
display:inline;
}
<form>
<input type="text" placeholder="Example field" class="inputfield">
<input type="submit" value="Submit" class="showonfocus">
</form>

You can use the onblur and onfocus events to manipulate your html elements. You can try something like,
HTML
<form>
<input type="text" placeholder="Example field" onblur="setVisible('hidden');" onfocus="setVisible('visible');">
<input id="submit" type="submit" value="Submit" style="visibility:hidden">
</form>
Javscript
function setVisible(state) {
document.getElementById("submit").style.visibility = state;
}
Here is the working DEMO: https://jsfiddle.net/qbotxpL6/
Hope this helps!

How to remove a cloned div in Jquery

<div id="file">
<input type="file" name="txtImage[]" class="upload" />
<input type="text" name="txtImageDesc[]" class="desc" />
</div>
<input type="button" value="Add" name="addButton" id="addButton" />
<input type="button" value="Remove" name="removeButton" id="removeButton" />
This is my html div i need to add and remove on button click and here is my jquery code
<script type='text/javascript'>
$('#addButton').click(function(){
$('.upload:last').clone().appendTo('#file');
$('.desc:last').clone().appendTo('#file');
});
$('#removeButton').click(function(){
$('.upload:last').clone().remove('#file');
$('.desc:last').clone().remove('#file');
});
</script>
Problem is The On add button, it works perfectly but on remove button, it does not.
I need to remove the cloned div when i click on remove button.

I think your remove code should be like this:
$('#removeButton').click(function(){
$('#file > .upload:last').remove();
$('#file > .desc:last').remove();
});

Try this:
$('#removeButton').click(function(){
$('.upload:last').remove();
$('.desc:last').remove();
});

You can also use this,
$('#removeButton').click(function(){
$('#file').css('display','none');
});

Triggering events in html using same button

I want to trigger an event with a button that changes the visibility of a set of elements (inputs of type text and button) from hidden to visible. Now everytime I click on the triggering button, I want a new set of the same elements to appear on a new line. How can that be done? Here is a snippet of the code:
<script type="text/javascript">
function generatenew()
{
document.add.property1.style.visibility="visible";
document.add.button2.style.visibility="visible";
document.add.button3.style.visibility="visible";
document.add.button4.style.visibility="visible";
}
</script>
</head>
<body>
<form name='add' method="post" action="">
<div id="div"></div>
<input type="button" value="+Add" onclick="generatenew();">
<input type="button" value="Edit" name="button2" style="visibility:hidden">
<input type="text" style="visibility:hidden" size="50" name="property1" placeholder="<street> <city> <ZIP> <country> <lockunitID>">
<input type="button" style="visibility:hidden" name="button3" value="open main door">
<input type="button" style="visibility:hidden" name="button4" value="open apartment door">
<div id="abc"><input type="button" value="save"></div>

If I well understood your question, all you have to do is putting a function that is triggered by an onClick event, (element.onClick=function();) You put all your input type tags in the function, and then you end your function bay calling appendChild method so that each click triggers the display of your elements.

ajax label on click text

I want to display the content of a label in a text fieldwith onClick event how can I do it,
Is there any specific method to do it or is there any other way.
Please help I am new to ajax.
Thanks

NO need of ajax for this you can do this by using jquery instead simply
In html:
<input type="text" name="txt1" value="" id="txt"/>
<label for="checking" id="label">checking</label>
<input type="submit" name="submit" value="Click" id="butt" />
In Javascript:
$("#butt").click(function(){
var lab_val = $("#label").text();
document.getElementByID("txt").value =lab_val;
// or $("#txt").val(lab_val);
});