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Masking input value after showing a few characters

I have an form input[type=text] that I would only like to show the first few characters, followed by the corresponding number of asterisks. For instance, if the value was banana, the input would display ban*** but would still submit banana.
A password field isn't the solution because I want to show some number of characters from the actual value.
I was thinking of saving the value in a data attribute and adding/remove on keydown, updating to asterisks on blur, and changing the value on submit but worry this could get messy. I'm using jQuery so I'm open to any plugins that may be out there as well.

Here I've keep a track of original text, and inside the edit I change chars after 3 into password char.
The proper password is then stored inside a data attribute data-orig, that you can then read when you submit data.
const i = $("input");
i.on("input", function () {
const $t = $(this);
const orig = $t.attr("data-orig") || "";
const v = $t.val().split("");
for (l = 1; l < orig.length && l < v.length; l += 1) {
v[l] = orig[l];
}
$t.attr("data-orig", v.join(""));
for (l = 3; l < v.length; l += 1) {
v[l] = "●";
}
$t.val(v.join(""));
});
$("button").on("click", function () {
console.log(i.attr("data-orig"));
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text">
<button>Get pwd</button>

I would use a hidden input field to store the real value and add a onchange-listener to it. So when it gets an Update the visible filed will get the update to. This function have to be triggerd onLoad to
HTML
<input type="hidden" name="realField" value="banana" onChange="update()">
<input type="text" readonly="readonly">
JS
function update(){
var text = $('input[name=realField]').val();
var s = '';
for(var i=3; i<text.length; ++i){
s+='*';
}
text = text.substr(0, Math.min(text.length, 3)) + s;
$('input[name=realField] + input').val(text);
}

Javascript validation on select input

I am trying to make a javascript validating form, and am a bit stuck on validating drop down inputs (select)
I have been using this so far but am unsure on how to implement the validation to the select options, if anyone could give me some tips that would be great.
Edit: Also, how would I implement email validation, e.g containing #, thanks
Thanks
<input id="firstname" onblur="validate('firstname')"></input>
Please enter your first name
Thanks
http://jsfiddle.net/ww2grozz/13/

you need to handle select as follow
var validated = {};
function validate(field) {
// Get the value of the input field being submitted
value = document.getElementById(field).value;
// Set the error field tag in the html
errorField = field + 'Error';
// Set the success field
successField = field + 'Success';
if (value != '') {
document.getElementById(successField).style.display = 'block';
document.getElementById(errorField).style.display = 'none';
validated[field] = true;
} else {
document.getElementById(successField).style.display = 'none';
document.getElementById(errorField).style.display = 'block';
validated[field] = false;
}
}
function SimulateSubmit() {
// Query your elements
var inputs = document.getElementsByTagName('input');
// Loop your elements
for (i = 0, len = inputs.length; i < len; i++) {
var name = inputs[i].id;
if (!validated[name]) {
// Call validate
validate(name);
// Prevent default
}
}
var all_select = document.getElementsByTagName("select"); // get al select box from the dom to validate
for (i = 0, len = all_select.length; i < len; i++) {
var name = all_select[i].id;
if (!validated[name]) {
// Call validate
validate(name);
// Prevent default
}
}
}
here the Working fiddle

using jQuery function
$('input').on('keyup', function() {
var isValid = $.trim($(this).val()) ? true : false;
// show result field is Valid
});

You must use <form> tag and set your action to it I have done that check this link and I have added select tag and set it to -1 by default for checking purpose while validating

Javascript for loop to change the name of textareas in a function

I have created 50 textareas with names def1,def2,def3.....,def50. In my body onLoad() function,I want the same value is set in all these textboxes.
Instead of writing the code 50 times, How can I write some Javascript code to set the value of the textarea, ie in a loop?

I suggest to read the MDC JavaScript guide, as loops and string concatenation are fairly basic operations:
for(var i = 1; i < 51; i++) {
var nameOfTextarea = 'def' + i;
// ...
}

I would give your textboxes ID's (not just names) if possible, and then do something like the following:
var namePrefix = "def";
for(var i = 1; i <= 50; ++i)
{
var textbox = getElementById(namePrefix + i);
// do something to textbox number i.
}

Try jquery for this:
<input type="text" id="t1"/>
<input type="text" id="t2"/>
<input type="text" id="t3"/>
The Jquery code:
var arr = [ "t1", "t2", "t3" ];
jQuery.each(arr, function() {
$("#"+this).val("hello");//$("#" + this).text("hello");
});
Here is the working demo

Try this.
var textareas = document.getElementsByTagName("textarea");
for(var i=0;i<textareas.length;i++){
if(textareas[i].id.indexOf("def") == 0){
textareas[i].value = textareas[i].id;
}
}

You can use tagname property but it will not work if you have some more textbox anywhere else in your page
function loader(){
for(var i=0;i<50;i++)
document.getElementsByName("def"+i)[0].value='Any Value';
}

Javascript Form submit is not working , issue only in internet explorer

I have form field and that form field gets submitted to the next page with the following javascript code.., the code is working fine in firefox but the form not getting submited in internet explorer.
function addarray(formId)
{
var ara = tmm.length;
//alert(ara);
for(var sds=0; sds < tmm.length; sds++)
{
var sss = tmm[sds];;
ara = ara+"*#*#*"+sss;
//alert(ara);
if(sss <= 0)
{
alert("\n\n\nYou should have atleast one submenu \n for each main menu \n\n");
return false;
}
}
var ddf = document.blcname.getElementsByTagName("input");
var i = 0;
while(i < ddf.length)
{
var dddd = ddf[i].type;
var vla = ddf[i].value;
//alert(i+"----"+vla+"-----"+dddd);
if(dddd=="text"){
if(vla == "")
{
//alert("Please fill all the required fields....");
return false;
}
}
i=i+1;
}
var setform = document.getElementById('arav');
setform.value = ara;
var formObj = document.getElementById(formId);
formObj.action = "get-code.php";
formObj.submit();
//document.blcname.submit();
}
thanks in advance

Try alternate ways of getting to this form. Give the form HTML id and a name attribute
Also watch out if you're using frames and the form is inside of a frame.
eg.
document.forms[0].submit() //if its the first form in the document
document.forms[1].submit() //if its the second form in the document
document.formName.submit() //using the name attribute.

Generic way to detect if html form is edited

I have a tabbed html form. Upon navigating from one tab to the other, the current tab's data is persisted (on the DB) even if there is no change to the data.
I would like to make the persistence call only if the form is edited. The form can contain any kind of control. Dirtying the form need not be by typing some text but choosing a date in a calendar control would also qualify.
One way to achieve this would be to display the form in read-only mode by default and have an 'Edit' button and if the user clicks the edit button then the call to DB is made (once again, irrespective of whether data is modified. This is a better improvement to what is currently existing).
I would like to know how to write a generic javascript function that would check if any of the controls value has been modified ?

In pure javascript, this would not be an easy task, but jQuery makes it very easy to do:
$("#myform :input").change(function() {
$("#myform").data("changed",true);
});
Then before saving, you can check if it was changed:
if ($("#myform").data("changed")) {
// submit the form
}
In the example above, the form has an id equal to "myform".
If you need this in many forms, you can easily turn it into a plugin:
$.fn.extend({
trackChanges: function() {
$(":input",this).change(function() {
$(this.form).data("changed", true);
});
}
,
isChanged: function() {
return this.data("changed");
}
});
Then you can simply say:
$("#myform").trackChanges();
and check if a form has changed:
if ($("#myform").isChanged()) {
// ...
}

I am not sure if I get your question right, but what about addEventListener? If you don't care too much about IE8 support this should be fine. The following code is working for me:
var form = document.getElementById("myForm");
form.addEventListener("input", function () {
console.log("Form has changed!");
});

In case JQuery is out of the question. A quick search on Google found Javascript implementations of MD5 and SHA1 hash algorithms. If you wanted, you could concatenate all form inputs and hash them, then store that value in memory. When the user is done. Concatenate all the values and hash again. Compare the 2 hashes. If they are the same, the user did not change any form fields. If they are different, something has been edited, and you need to call your persistence code.

Another way to achieve this is serialize the form:
$(function() {
var $form = $('form');
var initialState = $form.serialize();
$form.submit(function (e) {
if (initialState === $form.serialize()) {
console.log('Form is unchanged!');
} else {
console.log('Form has changed!');
}
e.preventDefault();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form>
Field 1: <input type="text" name="field_1" value="My value 1"> <br>
Field 2: <input type="text" name="field_2" value="My value 2"> <br>
Check: <input type="checkbox" name="field_3" value="1"><br>
<input type="submit">
</form>

Form changes can easily be detected in native JavaScript without jQuery:
function initChangeDetection(form) {
Array.from(form).forEach(el => el.dataset.origValue = el.value);
}
function formHasChanges(form) {
return Array.from(form).some(el => 'origValue' in el.dataset && el.dataset.origValue !== el.value);
}
initChangeDetection() can safely be called multiple times throughout your page's lifecycle: See Test on JSBin
For older browsers that don't support newer arrow/array functions:
function initChangeDetection(form) {
for (var i=0; i<form.length; i++) {
var el = form[i];
el.dataset.origValue = el.value;
}
}
function formHasChanges(form) {
for (var i=0; i<form.length; i++) {
var el = form[i];
if ('origValue' in el.dataset && el.dataset.origValue !== el.value) {
return true;
}
}
return false;
}

Here's how I did it (without using jQuery).
In my case, I wanted one particular form element not to be counted, because it was the element that triggered the check and so will always have changed. The exceptional element is named 'reporting_period' and is hard-coded in the function 'hasFormChanged()'.
To test, make an element call the function "changeReportingPeriod()", which you'll probably want to name something else.
IMPORTANT: You must call setInitialValues() when the values have been set to their original values (typically at page load, but not in my case).
NOTE: I do not claim that this is an elegant solution, in fact I don't believe in elegant JavaScript solutions. My personal emphasis in JavaScript is on readability, not structural elegance (as if that were possible in JavaScript). I do not concern myself with file size at all when writing JavaScript because that's what gzip is for, and trying to write more compact JavaScript code invariably leads to intolerable problems with maintenance. I offer no apologies, express no remorse and refuse to debate it. It's JavaScript. Sorry, I had to make this clear in order to convince myself that I should bother posting. Be happy! :)
var initial_values = new Array();
// Gets all form elements from the entire document.
function getAllFormElements() {
// Return variable.
var all_form_elements = Array();
// The form.
var form_activity_report = document.getElementById('form_activity_report');
// Different types of form elements.
var inputs = form_activity_report.getElementsByTagName('input');
var textareas = form_activity_report.getElementsByTagName('textarea');
var selects = form_activity_report.getElementsByTagName('select');
// We do it this way because we want to return an Array, not a NodeList.
var i;
for (i = 0; i < inputs.length; i++) {
all_form_elements.push(inputs[i]);
}
for (i = 0; i < textareas.length; i++) {
all_form_elements.push(textareas[i]);
}
for (i = 0; i < selects.length; i++) {
all_form_elements.push(selects[i]);
}
return all_form_elements;
}
// Sets the initial values of every form element.
function setInitialFormValues() {
var inputs = getAllFormElements();
for (var i = 0; i < inputs.length; i++) {
initial_values.push(inputs[i].value);
}
}
function hasFormChanged() {
var has_changed = false;
var elements = getAllFormElements();
for (var i = 0; i < elements.length; i++) {
if (elements[i].id != 'reporting_period' && elements[i].value != initial_values[i]) {
has_changed = true;
break;
}
}
return has_changed;
}
function changeReportingPeriod() {
alert(hasFormChanged());
}

Here's a polyfill method demo in native JavaScript that uses the FormData() API to detect created, updated, and deleted form entries. You can check if anything was changed using HTMLFormElement#isChanged and get an object containing the differences from a reset form using HTMLFormElement#changes (assuming they're not masked by an input name):
Object.defineProperties(HTMLFormElement.prototype, {
isChanged: {
configurable: true,
get: function isChanged () {
'use strict'
var thisData = new FormData(this)
var that = this.cloneNode(true)
// avoid masking: https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/reset
HTMLFormElement.prototype.reset.call(that)
var thatData = new FormData(that)
const theseKeys = Array.from(thisData.keys())
const thoseKeys = Array.from(thatData.keys())
if (theseKeys.length !== thoseKeys.length) {
return true
}
const allKeys = new Set(theseKeys.concat(thoseKeys))
function unequal (value, index) {
return value !== this[index]
}
for (const key of theseKeys) {
const theseValues = thisData.getAll(key)
const thoseValues = thatData.getAll(key)
if (theseValues.length !== thoseValues.length) {
return true
}
if (theseValues.some(unequal, thoseValues)) {
return true
}
}
return false
}
},
changes: {
configurable: true,
get: function changes () {
'use strict'
var thisData = new FormData(this)
var that = this.cloneNode(true)
// avoid masking: https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/reset
HTMLFormElement.prototype.reset.call(that)
var thatData = new FormData(that)
const theseKeys = Array.from(thisData.keys())
const thoseKeys = Array.from(thatData.keys())
const created = new FormData()
const deleted = new FormData()
const updated = new FormData()
const allKeys = new Set(theseKeys.concat(thoseKeys))
function unequal (value, index) {
return value !== this[index]
}
for (const key of allKeys) {
const theseValues = thisData.getAll(key)
const thoseValues = thatData.getAll(key)
const createdValues = theseValues.slice(thoseValues.length)
const deletedValues = thoseValues.slice(theseValues.length)
const minLength = Math.min(theseValues.length, thoseValues.length)
const updatedValues = theseValues.slice(0, minLength).filter(unequal, thoseValues)
function append (value) {
this.append(key, value)
}
createdValues.forEach(append, created)
deletedValues.forEach(append, deleted)
updatedValues.forEach(append, updated)
}
return {
created: Array.from(created),
deleted: Array.from(deleted),
updated: Array.from(updated)
}
}
}
})
document.querySelector('[value="Check"]').addEventListener('click', function () {
if (this.form.isChanged) {
console.log(this.form.changes)
} else {
console.log('unchanged')
}
})
<form>
<div>
<label for="name">Text Input:</label>
<input type="text" name="name" id="name" value="" tabindex="1" />
</div>
<div>
<h4>Radio Button Choice</h4>
<label for="radio-choice-1">Choice 1</label>
<input type="radio" name="radio-choice-1" id="radio-choice-1" tabindex="2" value="choice-1" />
<label for="radio-choice-2">Choice 2</label>
<input type="radio" name="radio-choice-2" id="radio-choice-2" tabindex="3" value="choice-2" />
</div>
<div>
<label for="select-choice">Select Dropdown Choice:</label>
<select name="select-choice" id="select-choice">
<option value="Choice 1">Choice 1</option>
<option value="Choice 2">Choice 2</option>
<option value="Choice 3">Choice 3</option>
</select>
</div>
<div>
<label for="textarea">Textarea:</label>
<textarea cols="40" rows="8" name="textarea" id="textarea"></textarea>
</div>
<div>
<label for="checkbox">Checkbox:</label>
<input type="checkbox" name="checkbox" id="checkbox" />
</div>
<div>
<input type="button" value="Check" />
</div>
</form>

I really like the contribution from Teekin above, and have implemented it.
However, I have expanded it to allow for checkboxes too using code like this:
// Gets all form elements from the entire document.
function getAllFormElements() {
// Return variable.
var all_form_elements = Array();
// The form.
var Form = document.getElementById('frmCompDetls');
// Different types of form elements.
var inputs = Form.getElementsByTagName('input');
var textareas = Form.getElementsByTagName('textarea');
var selects = Form.getElementsByTagName('select');
var checkboxes = Form.getElementsByTagName('CheckBox');
// We do it this way because we want to return an Array, not a NodeList.
var i;
for (i = 0; i < inputs.length; i++) {
all_form_elements.push(inputs[i]);
}
for (i = 0; i < textareas.length; i++) {
all_form_elements.push(textareas[i]);
}
for (i = 0; i < selects.length; i++) {
all_form_elements.push(selects[i]);
}
for (i = 0; i < checkboxes.length; i++) {
all_form_elements.push(checkboxes[i]);
}
return all_form_elements;
}
// Sets the initial values of every form element.
function setInitialFormValues() {
var inputs = getAllFormElements();
for (var i = 0; i < inputs.length; i++) {
if(inputs[i].type != "checkbox"){
initial_values.push(inputs[i].value);
}
else
{
initial_values.push(inputs[i].checked);
}
}
}
function hasFormChanged() {
var has_changed = false;
var elements = getAllFormElements();
var diffstring = ""
for (var i = 0; i < elements.length; i++) {
if (elements[i].type != "checkbox"){
if (elements[i].value != initial_values[i]) {
has_changed = true;
//diffstring = diffstring + elements[i].value+" Was "+initial_values[i]+"\n";
break;
}
}
else
{
if (elements[i].checked != initial_values[i]) {
has_changed = true;
//diffstring = diffstring + elements[i].value+" Was "+initial_values[i]+"\n";
break;
}
}
}
//alert(diffstring);
return has_changed;
}
The diffstring is just a debugging tool