Develop Reference

Issues displaying a dynamically updated HTML input value

I'm struggling to get the behaviour I need - as follows:
A HTML form is pre-populated with a value via jQuery. When the user focuses on the input field I want the form to clear. On blur from the form, the form should repopulate the form with the existing value.
I have a solution that clears and repopulates the form but it fails as soon as anything is typed in.
This is what I have so far:
var x = "Default";
$(function () {
$("input").attr({
"value": x
});
$("input").focus(function () {
$("input").attr({
"value": ""
});
});
$("input").blur(function () {
$("input").attr({
"value": x
});
});
});
https://jsfiddle.net/thepeted/p74kfdt8/6/
If I look in developer tools, I can see the input value is changing dynamically in the DOM, but in the case that the user has typed something in to the form, the display no longer updates.
I'd love to understand why this is happening (ie, why it works in one case and not the other). Also, if there is a better way of approaching the problem.

As pointed out by Stijn, best practice would be to use the placeholder attibute.
However if you do want to use a function for it. I would check on the focus if the value is the default value or not. If so, empty the input, if not, don't do anything.
On blur, you also only want to place the default value back if the value is empty... so check for that aswell.
var x = "Default";
$(function() {
$('input[type=text]').val(x);
$('input[type=text]').on('focus', function() {
var elem = $(this);
if (elem.val() == x)
elem.val('');
}).on("blur", function() {
var elem = $(this);
if (elem.val() == '')
elem.val(x);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" />

Your edited jsfiddle.
updated code:
$("input").blur(function () {
$("input").val(x);
});

Personnaly, I'd use the placeholder attribute as everyone pointed out. If you too are facing the need to support older browsers and some others that do not support the placeholder attribute, use this snippet I've made:
$('input[placeholder]').each(function(){
var $this = $(this);
$this.val($this.attr('placeholder')).css('color','888888');
$this.focus(function(){
if($(this).val() == $(this).attr('placeholder'))
$(this).val('').css('color','');
});
$this.blur(function(){
if($(this).val() == '')
$(this).val($(this).attr('placeholder')).css('color','888888');
});
});
This script will find all inputs with a placeholder attribute, give it's value to the input, and add the correct events. I've left the css calls just to show you where to put the codes to mimic the greyed text like modern browsers do.

Try this code
var x = "Default";
$(function () {
$("input").val(x);
$("input").focus(function () {
$("input").val("");
});
$("input").blur(function () {
$("input").val(x);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input type="text"/>

Converting Span to Input

I am developing web app, I have such a requirement that whenever user click on text inside span i need convert it into input field and on blur i need to convert it back to span again. So i am using following script in one of my jsp page.
Java Script:
<script type="text/javascript">
function covertSpan(id){
$('#'+id).click(function() {
var input = $("<input>", { val: $(this).text(),
type: "text" });
$(this).replaceWith(input);
input.select();
});
$('input').live('blur', function () {
var span=$("<span>", {text:$(this).val()});
$(this).replaceWith(span);
});
}
JSP Code:
<span id="loadNumId" onmouseover="javascript:covertSpan(this.id);">5566</span>
Now my problem is, everything works fine only for the first time. I mean whenever i click on the text inside span for the first time it converts into input field and again onblur it coverts back from input field to normal text. But if try once again to do so it won't work. Whats wrong with above script?

Would be good to change your dom structure to something like this (note that the span and the input are side by side and within a shared parent .inputSwitch
<div class="inputSwitch">
First Name: <span>John</span><input />
</div>
<div class="inputSwitch">
Last Name: <span>Doe</span><input />
</div>
Then we can do our JS like this, it will support selecting all on focus and tabbing to get to the next/previous span/input: http://jsfiddle.net/x33gz6z9/
var $inputSwitches = $(".inputSwitch"),
$inputs = $inputSwitches.find("input"),
$spans = $inputSwitches.find("span");
$spans.on("click", function() {
var $this = $(this);
$this.hide().siblings("input").show().focus().select();
}).each( function() {
var $this = $(this);
$this.text($this.siblings("input").val());
});
$inputs.on("blur", function() {
var $this = $(this);
$this.hide().siblings("span").text($this.val()).show();
}).on('keydown', function(e) {
if (e.which == 9) {
e.preventDefault();
if (e.shiftKey) {
$(this).blur().parent().prevAll($inputSwitches).first().find($spans).click();
} else {
$(this).blur().parent().nextAll($inputSwitches).first().find($spans).click();
}
}
}).hide();

I understand you think that element replacement is a nice thing, however, I would use a prompt to get the text. Why? It is a lot easier and actually a bit prettier for the user as well. If you are curious on how to do it, I show you.
html:
<span class='editable'>foobar</span>
js:
$(function()
{
$('span.editable').click(function()
{
var span = $(this);
var text = span.text();
var new_text = prompt("Change value", text);
if (new_text != null)
span.text(new_text);
});
});
http://jsfiddle.net/qJxhV/1/

First, you need to change your click handler to use live() as well. You should take note, though, that live() has been deprecated for quite a while now. You should be using on() in both cases instead.
Secondly, when you replace the input with the span, you don't give the element an id. Therefore, the element no longer matches the selector for your click handler.
Personally, I would take a different (and simpler) approach completely. I would have both the span and in the input in my markup side by side. One would be hidden while the other is shown. This would give you less chance to make mistakes when trying to recreate DOM elements and improve performance since you won't constantly be adding/removing elements from the DOM.

A more generic version of smerny's excellent answer with id's can be made by slightly altering two lines:
$input.attr("ID", "loadNum"); becomes $input.attr("ID", $(this).attr("ID")); -- this way, it simply takes the current id, and keeps it, whatever it is.
Similarly,
$span.attr("ID", "loadNum"); becomes $span.attr("ID", $(this).attr("ID"));
This simply allows the functions to be applied to any div. With two similar lines added, both id and class work fine. See example.

I have done little change in code, By using this input type cant be blank, it will back to its real value.
var switchToInput = function () {
var $input = $("<input>", {
val: $(this).text(),
type: "text",
rel : jQuery(this).text(),
});
$input.addClass("loadNum");
$(this).replaceWith($input);
$input.on("blur", switchToSpan);
$input.select();
};
var switchToSpan = function () {
if(jQuery(this).val()){
var $text = jQuery(this).val();
} else {
var $text = jQuery(this).attr('rel');
}
var $span = $("<span>", {
text: $text,
});
$span.addClass("loadNum");
$(this).replaceWith($span);
$span.on("click", switchToInput);
}
$(".loadNum").on("click", switchToInput);
jsFiddle:- https://jsfiddle.net/svsp3wqL/

How can I update a input using a div click event

I've got the following code in my web page, where I need to click on the input field and add values using the number pad provided! I use a script to clear the default values from the input when the focus comes to it, but I'm unable to add the values by clicking on the number pad since when I click on an element the focus comes from the input to the clicked number element. How can I resolve this issue. I tried the following code, but it doesn't show the number in the input.
var lastFocus;
$("#test").click(function(e) {
// do whatever you want here
e.preventDefault();
e.stopPropagation();
$("#results").append(e.html());
if (lastFocus) {
$("#results").append("setting focus back<br>");
setTimeout(function() {lastFocus.focus()}, 1);
}
return(false);
});
$("textarea").blur(function() {
lastFocus = this;
$("#results").append("textarea lost focus<br>");
});
Thank you.

The first thing I notice is your selector for the number buttons is wrong
$('num-button').click(function(e){
Your buttons have a class of num-button so you need a dot before the class name in the selector:
$('.num-button').click(function(e){
Secondly, your fiddle was never setting lastFocus so be sure to add this:
$('input').focus(function() {
lastFocus = this;
...
Thirdly, you add/remove the watermark when entering the field, but ot when trying to add numbers to it (that would result in "Watermark-text123" if you clicked 1, then 2 then 3).
So, encalpsulate your functionality in a function:
function addOrRemoveWatermark(elem)
{
if($(elem).val() == $(elem).data('default_val') || !$(elem).data('default_val')) {
$(elem).data('default_val', $(elem).val());
$(elem).val('');
}
}
And call that both when entering the cell, and when clicking the numbers:
$('input').focus(function() {
lastFocus = this;
addOrRemoveWatermark(this);
});
and:
$('.num-button').click(function(e){
e.preventDefault();
e.stopPropagation();
addOrRemoveWatermark(lastFocus);
$(lastFocus).val($(lastFocus).val() + $(this).children('span').html());
});
You'll see another change above - you dont want to use append when appends an element, you want to just concatenate the string with the value of the button clicked.
Here's a working branch of your code: http://jsfiddle.net/Zrhze/

This should work:
var default_val = '';
$('input').focus(function() {
lastFocus = $(this);
if($(this).val() == $(this).data('default_val') || !$(this).data('default_val')) {
$(this).data('default_val', $(this).val());
$(this).val('');
}
});
$('input').blur(function() {
if ($(this).val() == '') $(this).val($(this).data('default_val'));
});
var lastFocus;
$('.num-button').click(function(e){
e.preventDefault();
e.stopPropagation();
var text = $(e.target).text();
if (!isNaN(parseInt(text))) {
lastFocus.val(lastFocus.val() + text);
}
});
Live demo

Add the following function:
$('.num-button').live( 'click', 'span', function() {
$currObj.focus();
$currObj.val( $currObj.val() + $(this).text().trim() );
});
Also, add the following variable to global scope:
$currObj = '';
Here is the working link: http://jsfiddle.net/pN3eT/7/
EDIT
Based on comment, you wouldn't be needing the var lastFocus and subsequent code.
The updated fiddle lies here http://jsfiddle.net/pN3eT/28/

How to know with jQuery that a "select" input value has been changed?

I know that there is the change event handling in jQuery associated with an input of type select. But I want to know if the user has selected another value in the select element ! So I don't want to run code when the user select a new element in the select but I want to know if the user has selected a different value !
In fact there are two select elements in my form and I want to launch an ajax only when the two select elements has been changed. So how to know that the two elements has been changed ?

You can specifically listen for a change event on your chosen element by setting up a binding in your Javascript file.
That only solves half your problem though. You want to know when a different element has been selected.
You could do this by creating a tracking variable that updates every time the event is fired.
To start with, give your tracking variable a value that'll never appear in the dropdown.
// Hugely contrived! Don't ship to production!
var trackSelect = "I am extremely unlikely to be present";
Then, you'll need to set up a function to handle the change event.
Something as simple as:-
var checkChange = function() {
// If current value different from last tracked value
if ( trackSelect != $('#yourDD').val() )
{
// Do work associated with an actual change!
}
// Record current value in tracking variable
trackSelect = $('#yourDD').val();
}
Finally, you'll need to wire the event up in document.ready.
$(document).ready(function () {
$('#yourDD').bind('change', function (e) { checkChange() });
});

First of all you may use select event handler (to set values for some flags). This is how it works:
$('#select').change(function () {
alert($(this).val());
});​
Demo: http://jsfiddle.net/dXmsD/
Or you may store the original value somewhere and then check it:
$(document).ready(function () {
var val = $('#select').val();
...
// in some event handler
if ($('#select').val() != val) ...
...
});

First you need to store previous value of the selected option, then you should check if new selected value is different than stored value.
Check out the sample!
$(document).ready(function() {
var lastValue, selectedValue;
$('#select').change(function() {
selectedValue = $(this).find(':selected').val();
if(selectedValue == lastValue) {
alert('the value is the same');
}
else {
alert('the value has changed');
lastValue = selectedValue;
}
});
});​

You can save the value on page load in some hidden field.
like
$(document).ready(function(){
$('hiddenFieldId').val($('selectBoxId').val());
then on change you can grab the value of select:
});
$('selectBoxId').change(function(){
var valChng = $(this).val();
// now match the value with hidden field
if(valChng == $('hiddenFieldId').val()){
}
});

$("select").change(function () {
var str = "";
$("select option:selected").each(function () {
str += $(this).text() + " ";
});
$("div").text(str);
})
.change();
http://docs.jquery.com/Events/change

jQuery bind to Paste Event, how to get the content of the paste

I have a jquery token tagit plugin and I want to bind to the paste event to add items correctly.
I'm able to bind to the paste event like so:
.bind("paste", paste_input)
...
function paste_input(e) {
console.log(e)
return false;
}
How can I obtain the actual pasted content value?

There is an onpaste event that works in modern day browsers. You can access the pasted data using the getData function on the clipboardData object.
$("#textareaid").bind("paste", function(e){
// access the clipboard using the api
var pastedData = e.originalEvent.clipboardData.getData('text');
alert(pastedData);
} );
Note that bind and unbind are deprecated as of jQuery 3. The preferred call is to on.
All modern day browsers support the Clipboard API.
See also: In Jquery How to handle paste?

How about this: http://jsfiddle.net/5bNx4/
Please use .on if you are using jq1.7 et al.
Behaviour: When you type anything or paste anything on the 1st textarea the teaxtarea below captures the cahnge.
Rest I hope it helps the cause. :)
Helpful link =>
How do you handle oncut, oncopy, and onpaste in jQuery?
Catch paste input
EDIT:
Events list within .on() should be space-separated. Refer https://api.jquery.com/on/
code
$(document).ready(function() {
var $editor = $('#editor');
var $clipboard = $('<textarea />').insertAfter($editor);
if(!document.execCommand('StyleWithCSS', false, false)) {
document.execCommand('UseCSS', false, true);
}
$editor.on('paste keydown', function() {
var $self = $(this);
setTimeout(function(){
var $content = $self.html();
$clipboard.val($content);
},100);
});
});

I recently needed to accomplish something similar to this. I used the following design to access the paste element and value. jsFiddle demo
$('body').on('paste', 'input, textarea', function (e)
{
setTimeout(function ()
{
//currentTarget added in jQuery 1.3
alert($(e.currentTarget).val());
//do stuff
},0);
});

Another approach:
That input event will catch also the paste event.
$('textarea').bind('input', function () {
setTimeout(function () {
console.log('input event handled including paste event');
}, 0);
});

On modern browsers it's easy: just use the input event along with the inputType attribute:
$(document).on('input', 'input, textarea', function(e){
if (e.originalEvent.inputType == 'insertFromPaste') {
alert($(this).val());
}
});
https://codepen.io/anon/pen/jJOWxg

$(document).ready(function() {
$("#editor").bind('paste', function (e){
$(e.target).keyup(getInput);
});
function getInput(e){
var inputText = $(e.target).html(); /*$(e.target).val();*/
alert(inputText);
$(e.target).unbind('keyup');
}
});

This work on all browser to get pasted value. And also to creating common method for all text box.
$("#textareaid").bind("paste", function(e){
var pastedData = e.target.value;
alert(pastedData);
} )

You could compare the original value of the field and the changed value of the field and deduct the difference as the pasted value. This catches the pasted text correctly even if there is existing text in the field.
http://jsfiddle.net/6b7sK/
function text_diff(first, second) {
var start = 0;
while (start < first.length && first[start] == second[start]) {
++start;
}
var end = 0;
while (first.length - end > start && first[first.length - end - 1] == second[second.length - end - 1]) {
++end;
}
end = second.length - end;
return second.substr(start, end - start);
}
$('textarea').bind('paste', function () {
var self = $(this);
var orig = self.val();
setTimeout(function () {
var pasted = text_diff(orig, $(self).val());
console.log(pasted);
});
});

It would appear as though this event has some clipboardData property attached to it (it may be nested within the originalEvent property). The clipboardData contains an array of items and each one of those items has a getAsString() function that you can call. This returns the string representation of what is in the item.
Those items also have a getAsFile() function, as well as some others which are browser specific (e.g. in webkit browsers, there is a webkitGetAsEntry() function).
For my purposes, I needed the string value of what is being pasted. So, I did something similar to this:
$(element).bind("paste", function (e) {
e.originalEvent.clipboardData.items[0].getAsString(function (pStringRepresentation) {
debugger;
// pStringRepresentation now contains the string representation of what was pasted.
// This does not include HTML or any markup. Essentially jQuery's $(element).text()
// function result.
});
});
You'll want to perform an iteration through the items, keeping a string concatenation result.
The fact that there is an array of items makes me think more work will need to be done, analyzing each item. You'll also want to do some null/value checks.

I do it like so, this would work on most browsers used by humans
$("#couponCode").bind("change keyup input paste",function () {
const value= document.getElementById("couponCode").value;
});