Basically I need to check if the value is changed in a textbox on the 'blur' event so that if the value is not changed, I want to cancel the blur event.
If it possible to check it the value is changed by user on the blur event of an input HTML element?
I don't think there is a native way to do this. What I would do is, add a function to the focus event that saves the current value into a variable attached to the element (element.oldValue = element.value). You could check against that value onBLur.
Within the onblur event, you can compare the value against the defaultValue to determine whether a change happened:
<input onblur="if(this.value!=this.defaultValue){alert('changed');}">
The defaultValue will contain the initial value of the object, whereas the value will contain the current value of the object after a change has been made.
References:
value vs defaultValue
You can't cancel the blur event, you need to refocus in a timer. You could either set up a variable onfocus or set a hasChanged variable on the change event. The blur event fires after the change event (unfortunately, for this situation) otherwise you could have just reset the timer in the onchange event.
I'd take an approach similar to this:
(function () {
var hasChanged;
var element = document.getElementById("myInputElement");
element.onchange = function () { hasChanged = true; }
element.onblur = function () {
if (hasChanged) {
alert("You need to change the value");
// blur event can't actually be cancelled so refocus using a timer
window.setTimeout(function () { element.focus(); }, 0);
}
hasChanged = false;
}
})();
Why not just maintaining a custom flag on the input element?
input.addEventListener('change', () => input.hasChanged = true);
input.addEventListener('blur', () =>
{
if (!input.hasChanged) { return; }
input.hasChanged = false;
// Do your stuff
});
https://jsfiddle.net/d7yx63aj
Using Jquery events we can do this logic
Step1 : Declare a variable to compare the value
var lastVal ="";
Step 2: On focus get the last value from form input
$("#validation-form :input").focus(function () {
lastVal = $(this).val();
});
Step3:On blur compare it
$("#validation-form :input").blur(function () {
if (lastVal != $(this).val())
alert("changed");
});
You can use this code:
var Old_Val;
var Input_Field = $('#input');
Input_Field.focus(function(){
Old_Val = Input_Field.val();
});
Input_Field.blur(function(){
var new_input_val = Input_Field.val();
if (new_input_val != Old_Val){
// execute you code here
}
});
I know this is old, but I figured I'd put this in case anyone wants an alternative. This seems ugly (at least to me) but having to deal with the way the browser handles the -1 index is what was the challenge. Yes, I know it can be done better with the jquery.data, but I'm not that familiar with that just yet.
Here is the HTML code:
<select id="selected">
<option value="1">A</option>
<option value="2">B</option>
<option value="3">C</option>
</select>
Here is the javascript code:
var currentIndex; // set up a global variable for current value
$('#selected').on(
{ "focus": function() { // when the select is clicked on
currentIndex = $('#selected').val(); // grab the current selected option and store it
$('#selected').val(-1); // set the select to nothing
}
, "change": function() { // when the select is changed
choice = $('#selected').val(); // grab what (if anything) was selected
this.blur(); // take focus away from the select
//alert(currentIndex);
//setTimeout(function() { alert(choice); }, 0);
}
, "blur": function() { // when the focus is taken from the select (handles when something is changed or not)
//alert(currentIndex);
//alert($('#selected').val());
if ($('#selected').val() == null) { // if nothing has changed (because it is still set to the -1 value, or null)
$('#selected').val(currentIndex); // set the value back to what it originally was (otherwise it will stay at what was newly selected)
} else { // if anything has changed, even if it's the same one as before
if ($('#selected').val() == 2) { // in case you want to do something when a certain option is selected (in my case, option B, or value 2)
alert('I would do something');
}
}
}
});
Something like this. Using Kevin Nadsady's above suggestion of
this.value!=this.defaultValue
I use a shared CSS class on a bunch of inputs then do:
for (var i = 0; i < myInputs.length; i++) {
myInputs[i].addEventListener('blur', function (evt) {
if(this.value!=this.defaultValue){
//value was changed now do your thing
}
});
myInputs[i].addEventListener('focus', function (evt) {
evt.target.setAttribute("value",evt.target.value);
});
}
Even if this is an old post, I thought i'd share a way to do this with simple javascript.
The javascript portion:
<script type="text/javascript">
function HideLabel(txtField){
if(txtField.name=='YOURBOXNAME'){
if(txtField.value=='YOURBOXNAME')
txtField.value = '';
else
txtField.select();
}
}
function ShowLabel(YOURBOXNAME){
if(txtField.name=='YOURBOXNAME'){
if(txtField.value.trim()=='')
txtField.value = 'YOURDEFAULTVALUE';
}
}
</script>
Now the text field in your form:
<input type="text" id="input" name="YOURBOXNAME" value="1" onfocus="HideLabel(this)"
onblur="ShowLabel(this)">
And bewn! No Jquery needed. just simple javascript. cut and paste those bad boys. (remember to put your javascript above the body in your html)
Similar to #Kevin Nadsady's post, the following will work in native JS functions and JQuery listener events. Within the onblur event, you can compare the value against the defaultValue:
$(".saveOnChange").on("blur", function () {
if (this.value != this.defaultValue) {
//Set the default value to the new value
this.defaultValue = this.value;
//todo: save changes
alert("changed");
}
});
The idea is to have a hidden field to keep the old value and whenever the onblur event happens, check the change and update the hidden value with the current text value
string html = "<input type=text id=it" + row["cod"] + "inputDesc value='"
+ row["desc"] + "' onblur =\"if (this.value != document.getElementById('hd" + row["cod"].ToString() +
"inputHiddenDesc').value){ alert('value change'); document.getElementById('hd" + row["cod"].ToString() +
"inputHiddenDesc').value = this.value; }\"> " +
"<input type=hidden id=hd" + row["cod"].ToString() + "inputHiddenDesc value='" + row["desc"] + "'>";
Related
I want a function to be called whenever there is any change within my text area, i.e. char typed, removed, cut, pasted etc.
Currently I am using:
onkeyup || onmousemove = function();
This seems to only be calling onmousemove, what can I use to call my function on ANY change to the textarea.
I am creating this JS as a string to add it as a parameter to the creation of a text_area using codeigniteras described here at form_input section
e.g:
$js= 'onkeyup || onmousemove = "function()"';
echo text_area('name', " ", $js);
There's no way to combine multiple HTML attribute assignment, you have to do them separately. Try:
text_input('name', ' ', 'onkeyup="function()" onmousemove="function()"');
try this :
$('#element').on('keyup keypress blur change', function() {
...
});
Just give textarea an id say myId and bind events to it to trigger handler.
var element = document.getElementById("myId");
var myEvents = "oninput onchange onkeyup onpaste".split(" ");
var handler = function (e) {
};
for (var i=0, len = myEvents.length; i < len; i++) {
element.addEventListener(myEvents[i], handler, false);
}
Try something like below
Example
<textarea id='textarea1'>data</textarea>
//....................
$("textarea").bind('input propertychange', function(){
alert($(this).val());
});
Note: Use jquery plugin
DEMO
If you want to prevent simultaneous triggers then use the below code
<textarea id="textarea"></textarea>
//.......
var text = "";
$("#textarea").on("change keyup paste", function() {
var Val = $(this).val();
if(Val == text) {
return; //prevent multiple simultaneous triggers
}
text = Val;
alert("changed!");
});
DEMO2
I have a select box called "requestHistoryRequestType". I'm trying to write some jQuery so that when the value of that select box is changed I call a function that adds a class and attribute to a field and appends a span to the field that I pass in as a parameter.
The problem is if a user chooses EXPAPP or EXPDEN but then changes their selection to NA it should remove the added stuff from the previous fields and add the same stuff to a different field. Kinda hard to explain, but ask questions away! I'm kinda new to writing complex jQuery like this.
The function that does the adding classes and such:
function requiredField(requiredField) {
$(requiredField).parent().addClass('has-error');
$(requiredField).attr('data-rule-required', true);
$("label[for='" + requiredField.replace('#', '') + "']").append("<span style='color:#b94a48;' class='has-error has-tooltip' data-placement='right' title='Required Field'>*</span>");
}
The actual on change listener:
//Validations for EXPAPP, EXPDEN, and NA
$("#requestHistoryRequestType").on("change", function() {
if ($("#requestHistoryRequestType").val() === "EXPAPP" || $("#requestHistoryRequestType").val() === "EXPDEN"){
requiredField("#requestHistoryVerbalDateTime");
requiredField("#requestHistoryWrittenDateTime");
} else if ($("#requestHistoryRequestType").val() === "NA") {
requiredField("#requestHistoryComments");
}
});
Thanks Stack!
Create a function that would remove the added stuff from all fields and call it before requiredField() calls:
function removeRequiredFields()
{
var $fields = $("#requestHistoryVerbalDateTime, #requestHistoryWrittenDateTime, #requestHistoryComments");
$fields.parent().removeClass('has-error');
$fields.attr('data-rule-required', false);
$fields.each(function() {
$("label[for='"+$(this).attr('id')+"']").find("[title='Required Field']").remove();
});
}
Or you can pass $fields from the event handler to removeRequiredFields() instead of hardcoding it there, for added flexibility.
I would just have a separate function for when you select a "NA" rather then trying to build that functionality into the same function.
I'll rewrite your event handler to make it a bit cleaner as well (IMO).
//Validations for EXPAPP, EXPDEN, and NA
$("#requestHistoryRequestType").on("change", function() {
var selectedVal = $(this).val();
if (selectedVal === "EXPAPP" || selectedVal === "EXPDEN"){
requiredField("#requestHistoryVerbalDateTime");
requiredField("#requestHistoryWrittenDateTime");
} else if (selectedVal === "NA") {
requiredField("#requestHistoryComments");
}
});
This way you are not hitting the DOM a potential 3 time to test your conditions every time an event is triggered. A minor change but probably a useful one as you get into more complex and larger jQuery selectors.
Edit: If you feel you MUST do it in one function then you can call the function with both elements you want to append
function requiredField(requiredField1, requiredField2) {
if (requiredField2 != null){
$(requiredField1,requiredField1).parent().addClass('has-error');
$(requiredField1,requiredField1).attr('data-rule-required', true);
var requiredLabel = "<span style='color:#b94a48;' class='has-error has-tooltip' data-placement='right' title='Required Field'>*</span>"
$("label[for='" + requiredField1.replace('#', '') + "']").append(requiredLabel);
$("label[for='" + requiredField2.replace('#', '') + "']").append(requiredLabel);
}
else {
//remove multiple element classes and add it to the single one representing the "NA"
}
}
This is based on you only ever having one case where you would be passing a single "requiredField" on a case of a "NA"
I am not much of a JavaScript guru, so I would need help with a simple code.
I have a button that clears the value of an input field.
I would like it (the button) to be hidden if input field is empty and vice versa (visible if there is text inside the input field).
The solution can be pure JavaScript or jQuery, it doesn't matter. The simpler, the better.
$("input").keyup(function () {
if ($(this).val()) {
$("button").show();
}
else {
$("button").hide();
}
});
$("button").click(function () {
$("input").val('');
$(this).hide();
});
http://jsfiddle.net/SVxbW/
if(!$('input').val()){
$('#button').hide();
}
else {
$('#button').show();
}
In it's simplest form ;)
to do this without jQuery (essentially the same thing others already did, just pure js). It's pretty simple, but I've also added a few comments.
<body>
<input type="text" id="YourTextBox" value="" />
<input type="button" id="YourButton" value="Click Me" />
<script type="text/javascript">
var textBox = null;
var button = null;
var textBox_Change = function(e) {
// just calls the function that sets the visibility
button_SetVisibility();
};
var button_SetVisibility = function() {
// simply check if the visibility is set to 'visible' AND textbox hasn't been filled
// if it's already visibile and the text is blank, hide it
if((button.style.visibility === 'visible') && (textBox.value === '')) {
button.style.visibility = 'hidden';
} else {
// show it otherwise
button.style.visibility = 'visible';
}
};
var button_Click = function(e) {
// absolutely not required, just to add more to the sample
// this will set the textbox to empty and call the function that sets the visibility
textBox.value = '';
button_SetVisibility();
};
// wrap the calls inside anonymous function
(function() {
// define the references for the textbox and button here
textBox = document.getElementById("YourTextBox");
button = document.getElementById("YourButton");
// some browsers start it off with empty, so we force it to be visible, that's why I'll be using only chrome for now on...
if('' === button.style.visibility) { button.style.visibility = 'visible'; }
// assign the event handlers for the change and click event
textBox.onchange = textBox_Change;
button.onclick = button_Click;
// initialize calling the function to set the button visibility
button_SetVisibility();
})();
</script>
</body>
Note: I've written and tested this in IE9 and Chrome, make sure you test it in other browsers. Also, I've added this fiddle so you can see it working.
You can use $('selector').hide() to hide an element from view and $('selector').show() to display it again.
Even better, you can use $('selector').toggle() to have it show and hide without any custom logic.
First hide the button on page load:
jQuery(document).ready(function() {
jQuery("#myButton").hide();
});
Then attach an onChange handler, which will hide the button whenever the contents of the text-field are empty. Otherwise, it shows the button:
jQuery("#myText").change(function() {
if(this.value.replace(/\s/g, "") === "") {
jQuery("#myButton").hide();
} else {
jQuery("#myButton").show();
}
});
You will also need to hide the button after clearing the input:
jQuery("#myButton").click(function() {
jQuery("#myInput").val("");
jQuery(this).hide();
});
I have a page that needs to do two things at once:
Listen all the time for input from a scanner (which presents as keyboard input), and notice when a string is entered in the right format.
Listen for a user focussing on a particular dropdown, and typing a set of initials - when a set of initials is entered that matches the title attribute of an item in the dropdown, focus on that dropdown.
I can do either of these things separately, but not together. Code:
// Listen for input when userlist is in focus.
$("#userlist").keypress(function (e) {
initials += String.fromCharCode(e.which).toUpperCase();
$(this).find("option").filter(function () {
return $(this).attr("title").toUpperCase().indexOf(initials) === 0;
}).first().attr("selected", true);
// uses timer to check for time between keypresses
return false;
});
// Listen for scanner input all the time.
var input = '',
r1 = /^~{1}$/,
r2 = /^~{1}\d+$/,
r3 = /^~{1}\d+\.$/,
r4 = /^~{1}\d+\.\d+$/,
r5 = /^~{1}\d+\.\d+~{1}$/;
$(window).keypress(function(e) {
// when input matches final regex, do something
}
If I have both, then while the user is focussed on the dropdown, the page does not 'hear' the input from the scanner.
How can I combine the two together to make sure the page reacts to scanner input, even while the user is focussed on the dropdown?
It's because you are overriding the listener on the window object with a listener on the keypress object. I would do something like this:
var input = '',
r1 = /^~{1}$/,
r2 = /^~{1}\d+$/,
r3 = /^~{1}\d+\.$/,
r4 = /^~{1}\d+\.\d+$/,
r5 = /^~{1}\d+\.\d+~{1}$/;
function checkRegex(e) { /* Check */ }
// Listen for input when userlist is in focus.
$("#userlist").keypress(function (e) {
checkRegex(e);
initials += String.fromCharCode(e.which).toUpperCase();
$(this).find("option").filter(function () {
return $(this).attr("title").toUpperCase().indexOf(initials) === 0;
}).first().attr("selected", true);
// uses timer to check for time between keypresses
return false;
});
// Listen for scanner input all the time.
$(window).keypress(function(e) {
checkRegex(e);
}
Wouldn't delegate give you the necessary control? You could then check for the event target and respond accordingly?
ie:
$(window).delegate('keypress', function(e){
if ($(e.target).attr('id') == 'userlist'){
// something
}else{
//something else
}
});
You don't need two handlers. Just have a single handler at the window level and then check which element raised the event:
$(window).keypress(function(e) {
var $target = $(e.target);
if ($target.is("#userlist")) {
initials += String.fromCharCode(e.which).toUpperCase();
$(this).find("option").filter(function () {
return $(this).attr("title").toUpperCase().indexOf(initials) === 0;
}).first().attr("selected", true);
// uses timer to check for time between keypresses
return false;
} else {
// when input matches final regex, do something
}
});
This is probably way more complex than you'd like it to be, but I think it'll fit your purpose.
I tried to make it in the style of a jQuery plugin, and allow you to attach it to any specific object (and customize of it should override bubbling up through the DOM (in the case of your combo box) in addition to allow for windows, etc.
Anyways, try it out and see what you think. I can make modifications if necessary, just need to know what they are.
Working Example: http://www.jsfiddle.net/bradchristie/xSMQd/4/
;(function($){
$.keyListener = function(sel, options){
// avoid scope issues by using base instead of this
var base = this;
// Setup jQuery DOM elements
base.$sel = $(sel);
base.sel = sel;
base.keyPresses = '';
base.validater = null;
// add a reverse reference to the DOM object
base.$sel.data('keyListener', base);
// create an initialization function we can call
base.init = function(){
base.opts = $.extend({}, $.keyListener.defaultOptions, options);
base.$sel.keypress(function(e){
base.keyPresses += String.fromCharCode(e.which);
if (base.validator != null)
clearTimeout(base.validator);
if (base.keyPresses != '')
base.validator = setTimeout(base.validateInput, base.opts.callbackDelay);
if (base.opts.preventDefault)
e.preventDefault();
else if (base.opts.stopPropagation)
e.stopPropagation();
});
};
base.validateInput = function(){
var filter = base.opts.filter;
var reCompare = (typeof(filter)=='object'
? filter.constructor.toString().match(/regexp/i)!==null
: false);
// exception when the input is cleared out
var input = base.sel.constructor.toString().match(/HTMLInputElement|HTMLSelectElement|HTMLTextAreaElement/i);
if (input && (!base.opts.preventDefault && base.$sel.val() == ''))
base.keyPresses = '';
// regular expression match
if (reCompare){
if (base.keyPresses.match(filter))
base.validateSuccess();
else
base.validateFailure();
// traditional string match
}else if (typeof(filter)=='string'){
if (base.keyPresses==filter)
base.validateSuccess();
else
base.validateFailure();
}
// reset string
base.keyPresses = '';
};
base.validateSuccess = function(){
if (typeof(base.opts.success)=='function')
base.opts.success(base.keyPresses);
};
base.validateFailure = function(){
if (typeof(base.opts.failure)=='function')
base.opts.failure(base.keyPresses);
};
// run the initializer
base.init();
};
$.keyListener.defaultOptions = {
// time to wait before triggering callback
// Give it time to accumulate the key presses and send it off
// as a compiled package
callbackDelay: 1000,
// Filter to apply to the input (can be a string match or a regular expression)
filter: /.*/,
// functions to callback when a match has or hasn't been made
success: function(i){},
failure: function(i){},
// would you like this to completely override key input?
preventDefault: false,
// stop it from going up the DOM tree (first object to grab the keypress
// gets it)
stopPropagation: true,
};
$.fn.extend({
keyListener: function(options){
// use return to allow jQuery to chain methods
return this.each(function(){
(new $.keyListener(this, options));
});
}
});
})(jQuery);
$('#listen-scanner,#listen-combo,#listen-text').add(window).keyListener({
filter: /^\d+$/,
success: function(input){
$('#output-scanner').text('Match!: '+input);
},
failure: function(input){
$('#output-scanner').text('No Match: '+input);
},
stopPropagation: true
});
And the HTML I tried it on:
<input type="text" id="listen-scanner" /><span id="output-scanner"></span><br />
<select id="listen-combo">
<option value="AA">Aardvarc</option>
<option value="AB">Abracabra</option>
<option value="AC">Accelerate</option>
<option value="AD">Adult</option>
</select><span id="output-combo"></span>
<textarea id="listen-text"></textarea>
I'd like to track changes in inputs in a form via javascript. My intent is (but not limited) to
enable "save" button only when something has changed
alert if the user wants to close the page and something is not saved
Ideas?
Loop through all the input elements, and put an onchange handler on each. When that fires, set a flag which lets you know the form has changed. A basic version of that would be very easy to set up, but wouldn't be smart enough to recognize if someone changed an input from "a" to "b" and then back to "a". If it were important to catch that case, then it'd still be possible, but would take a bit more work.
Here's a basic example in jQuery:
$("#myForm")
.on("input", function() {
// do whatever you need to do when something's changed.
// perhaps set up an onExit function on the window
$('#saveButton').show();
})
;
Text form elements in JS expose a .value property and a .defaultValue property, so you can easily implement something like:
function formChanged(form) {
for (var i = 0; i < form.elements.length; i++) {
if(form.elements[i].value != form.elements[i].defaultValue) return(true);
}
return(false);
}
For checkboxes and radio buttons see whether element.checked != element.defaultChecked, and for HTML <select /> elements you'll need to loop over the select.options array and check for each option whether selected == defaultSelected.
You might want to look at using a framework like jQuery to attach handlers to the onchange event of each individual form element. These handlers can call your formChanged() code and modify the enabled property of your "save" button, and/or attach/detach an event handler for the document body's beforeunload event.
Here's a javascript & jquery method for detecting form changes that is simple. It disables the submit button until changes are made. It detects attempts to leave the page by means other than submitting the form. It accounts for "undos" by the user, it is encapsulated within a function for ease of application, and it doesn't misfire on submit. Just call the function and pass the ID of your form.
This function serializes the form once when the page is loaded, and again before the user leaves the page. If the two form states are different, the prompt is shown.
Try it out: http://jsfiddle.net/skibulk/ev5rE/
function formUnloadPrompt(formSelector) {
var formA = $(formSelector).serialize(), formB, formSubmit = false;
// Detect Form Submit
$(formSelector).submit( function(){
formSubmit = true;
});
// Handle Form Unload
window.onbeforeunload = function(){
if (formSubmit) return;
formB = $(formSelector).serialize();
if (formA != formB) return "Your changes have not been saved.";
};
// Enable & Disable Submit Button
var formToggleSubmit = function(){
formB = $(formSelector).serialize();
$(formSelector+' [type="submit"]').attr( "disabled", formA == formB);
};
formToggleSubmit();
$(formSelector).change(formToggleSubmit);
$(formSelector).keyup(formToggleSubmit);
}
// Call function on DOM Ready:
$(function(){
formUnloadPrompt('form');
});
Try
function isModifiedForm(form){
var __clone = $(form).clone();
__clone[0].reset();
return $(form).serialize() == $(__clone).serialize();
}
Hope its helps ))
If your using a web app framework (rails, ASP.NET, Cake, symfony), there should be packages for ajax validation,
http://webtecker.com/2008/03/17/list-of-ajax-form-validators/
and some wrapper on onbeforeunload() to warn users taht are about to close the form:
http://pragmatig.wordpress.com/2008/03/03/protecting-userdata-from-beeing-lost-with-jquery/
Detecting Unsaved Changes
I answered a question like this on Ars Technica, but the question was framed such that the changes needed to be detected even if the user does not blur a text field (in which case the change event never fires). I came up with a comprehensive script which:
enables submit and reset buttons if field values change
disables submit and reset buttons if the form is reset
interrupts leaving the page if form data has changed and not been submitted
supports IE 6+, Firefox 2+, Safari 3+ (and presumably Opera but I did not test)
This script depends on Prototype but could be easily adapted to another library or to stand alone.
$(document).observe('dom:loaded', function(e) {
var browser = {
trident: !!document.all && !window.opera,
webkit: (!(!!document.all && !window.opera) && !document.doctype) ||
(!!window.devicePixelRatio && !!window.getMatchedCSSRules)
};
// Select form elements that won't bubble up delegated events (eg. onchange)
var inputs = $('form_id').select('select, input[type="radio"], input[type="checkbox"]');
$('form_id').observe('submit', function(e) {
// Don't bother submitting if form not modified
if(!$('form_id').hasClassName('modified')) {
e.stop();
return false;
}
$('form_id').addClassName('saving');
});
var change = function(e) {
// Paste event fires before content has been pasted
if(e && e.type && e.type == 'paste') {
arguments.callee.defer();
return false;
}
// Check if event actually results in changed data
if(!e || e.type != 'change') {
var modified = false;
$('form_id').getElements().each(function(element) {
if(element.tagName.match(/^textarea$/i)) {
if($F(element) != element.defaultValue) {
modified = true;
}
return;
} else if(element.tagName.match(/^input$/i)) {
if(element.type.match(/^(text|hidden)$/i) && $F(element) != element.defaultValue) {
modified = true;
} else if(element.type.match(/^(checkbox|radio)$/i) && element.checked != element.defaultChecked) {
modified = true;
}
}
});
if(!modified) {
return false;
}
}
// Mark form as modified
$('form_id').addClassName('modified');
// Enable submit/reset buttons
$('reset_button_id').removeAttribute('disabled');
$('submit_button_id').removeAttribute('disabled');
// Remove event handlers as they're no longer needed
if(browser.trident) {
$('form_id').stopObserving('keyup', change);
$('form_id').stopObserving('paste', change);
} else {
$('form_id').stopObserving('input', change);
}
if(browser.webkit) {
$$('#form_id textarea').invoke('stopObserving', 'keyup', change);
$$('#form_id textarea').invoke('stopObserving', 'paste', change);
}
inputs.invoke('stopObserving', 'change', arguments.callee);
};
$('form_id').observe('reset', function(e) {
// Unset form modified, restart modified check...
$('reset_button_id').writeAttribute('disabled', true);
$('submit_button_id').writeAttribute('disabled', true);
$('form_id').removeClassName('modified');
startObservers();
});
var startObservers = (function(e) {
if(browser.trident) {
$('form_id').observe('keyup', change);
$('form_id').observe('paste', change);
} else {
$('form_id').observe('input', change);
}
// Webkit apparently doesn't fire oninput in textareas
if(browser.webkit) {
$$('#form_id textarea').invoke('observe', 'keyup', change);
$$('#form_id textarea').invoke('observe', 'paste', change);
}
inputs.invoke('observe', 'change', change);
return arguments.callee;
})();
window.onbeforeunload = function(e) {
if($('form_id').hasClassName('modified') && !$('form_id').hasClassName('saving')) {
return 'You have unsaved content, would you really like to leave the page? All your changes will be lost.';
}
};
});
I would store each fields value in a variable when the page loads, then compare those values when the user unloads the page. If any differences are detected you will know what to save and better yet, be able to specifically tell the user what data will not be saved if they exit.
// this example uses the prototype library
// also, it's not very efficient, I just threw it together
var valuesAtLoad = [];
var valuesOnCheck = [];
var isDirty = false;
var names = [];
Event.observe(window, 'load', function() {
$$('.field').each(function(i) {
valuesAtLoad.push($F(i));
});
});
var checkValues = function() {
var changes = [];
valuesOnCheck = [];
$$('.field').each(function(i) {
valuesOnCheck.push($F(i));
});
for(var i = 0; i <= valuesOnCheck.length - 1; i++ ) {
var source = valuesOnCheck[i];
var compare = valuesAtLoad[i];
if( source !== compare ) {
changes.push($$('.field')[i]);
}
}
return changes.length > 0 ? changes : [];
};
setInterval(function() { names = checkValues().pluck('id'); isDirty = names.length > 0; }, 100);
// notify the user when they exit
Event.observe(window, 'beforeunload', function(e) {
e.returnValue = isDirty ? "you have changed the following fields: \r\n" + names + "\r\n these changes will be lost if you exit. Are you sure you want to continue?" : true;
});
I've used dirtyforms.js. Works well for me.
http://mal.co.nz/code/jquery-dirty-forms/
To alert the user before closing, use unbeforeunload:
window.onbeforeunload = function() {
return "You are about to lose your form data.";
};
I did some Cross Browser Testing.
On Chrome and Safari this is nice:
<form onchange="validate()">
...
</form>
For Firefox + Chrome/Safari I go with this:
<form onkeydown="validate()">
...
<input type="checkbox" onchange="validate()">
</form>
Items like checkboxes or radiobuttons need an own onchange event listener.
Attach an event handler to each form input/select/textarea's onchange event. Setting a variable to tell you if you should enable the "save" button. Create an onunload hander that checks for a dirty form too, and when the form is submitted reset the variable:
window.onunload = checkUnsavedPage;
var isDirty = false;
var formElements = //Get a reference to all form elements
for(var i = 0; len = formElements.length; i++) {
//Add onchange event to each element to call formChanged()
}
function formChanged(event) {
isDirty = false;
document.getElementById("savebtn").disabled = "";
}
function checkUnsavedPage() {
if (isDirty) {
var isSure = confirm("you sure?");
if (!isSure) {
event.preventDefault();
}
}
}
Here's a full implementation of Dylan Beattie's suggestion:
Client/JS Framework for "Unsaved Data" Protection?
You shouldn't need to store initial values to determine if the form has changed, unless you're populating it dynamically on the client side (although, even then, you could still set up the default properties on the form elements).
You can also check out this jQuery plugin I built at jQuery track changes in forms plugin
See the demo here and download the JS here
If you are open to using jQuery, see my answer a similar question:
Disable submit button unless original form data has changed.
I had the same challenge and i was thinking of a common solution. The code below is not perfect, its from initial r&d. Following are the steps I used:
1) Move the following JS to a another file (say changeFramework.js)
2) Include it in your project by importing it
3) In your html page, whichever control needs monitoring, add the class "monitorChange"
4) The global variable 'hasChanged' will tell, if there is any change in the page you working on.
<script type="text/javascript" id="MonitorChangeFramework">
// MONITOR CHANGE FRAMEWORK
// ALL ELEMENTS WITH CLASS ".monitorChange" WILL BE REGISTERED FOR CHANGE
// ON CHANGE IT WILL RAISE A FLAG
var hasChanged;
function MonitorChange() {
hasChanged = false;
$(".monitorChange").change(function () {
hasChanged = true;
});
}
Following are the controls where I used this framework:
<textarea class="monitorChange" rows="5" cols="10" id="testArea"></textarea></br>
<div id="divDrinks">
<input type="checkbox" class="chb monitorChange" value="Tea" />Tea </br>
<input type="checkbox" class="chb monitorChange" value="Milk" checked='checked' />Milk</br>
<input type="checkbox" class="chb monitorChange" value="Coffee" />Coffee </br>
</div>
<select id="comboCar" class="monitorChange">
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="mercedes">Mercedes</option>
<option value="audi">Audi</option>
</select>
<button id="testButton">
test</button><a onclick="NavigateTo()">next >>> </a>
I believe there can be huge improvement in this framework. Comment/Changes/feedbacks are welcome. :)