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Prevent From Writing on TextArea using Bind Event "input propertychange"

I am handling the content inside a textarea using binding a function to the event "input propertychange"
Like this:
$('#textarea').bind('input propertychange', function () {
var textarea = document.getElementById('textarea');
window.lastLineWriting = textarea.value.substr(0, textarea.value.length).split("\n").length;
var writingOnLine = textarea.value.substr(0, textarea.selectionStart).split("\n").length;
if (writingOnLine < window.lastLineWriting) {
//dont write on textarea
}
});
I don't know how to prevent the char typed by the user's keyboard to appear on the textarea... Inside that if I want to prevent the text to be inserted on textarea..
How can I do this?

you could easily stop the user from typing with this code, using jQuery:
$('textarea').bind('keypress', function (e) {
e.preventDefault();
return false;
});
NOTE:
this code will prevent the user from typing in all the textareas, to bind it specifically to one or some selected elements, you must change the selector to the desired elements.

var editable = false // Your Condition
if(editable != "true"){
$("#textarea" ).attr("disabled",true);
}

jQuery on click starts working correctly after second button click

(Fiddle: http://jsfiddle.net/qdP3j/)
I have this div:
<div id="addContactList"></div>
I use AJAX and change its innerHTML with something like:
<div id="<%= data[i].id %>">
<img src="<%= picture %>">
<button class="addAsFriend">Add as Friend</button>
</div>
In my JS, I have
$('#addContactList').on('click', '.addAsFriend', function () {
$(this).text('Request sent!');
$(this).attr('disabled','disabled');
});
What happens is that when I click on a button for the first time, I see that the click function ran; "Request sent!" is being shown but it immediately reverts back to the initial button. When I click a second time, it works fine.
I tried using event.stopPropagation and preventDefault but same issue happens.
As stated, it probably comes from the AJAX part:
Basically, I have 3 input fields on a page, and users can enter data in them. If there is data in the fields, they are posted and I use the data to query the database. There is a delay function of 250ms to prevent posting immediately every time a letter is typed.
var addContactsList = document.getElementById('addContactList');
$('#addContactForm').on('keyup change', function () {
var self = this;
// Add a short delay to not post for every letter typed quickly
delay(function() {
var userSearchData = {};
userSearchData.userId = 23;
$.each(['email', 'username', 'fullName'], function (_, el) {
var val = $(self).find('input[name="' + el + '"]').val();
if (val.length >= 3) {
userSearchData[el] = val;
}
});
if ( !isEmpty(userSearchData) ) {
$.post('/post/addContact', { userSearchData: userSearchData }, function (data) {
if (data) {
new EJS({url: '/templates/addAContact.ejs'}).update('addContactList', { data: data })
} else {
addContactsList.innerHTML = '';
}
});
} else {
addContactsList.innerHTML = '';
}
}, 225 );
});

It's because of the "keyup change". Change was being triggered again when clicking elsewhere (the add friend button).
Now though the problem is when people use the autocomplete feature using the mouse, it will not trigger because change isn't there anymore.

As you noticed, the change event fires when your input field loses focus (when you click on the button). You can keep the change event, and check if the change event is firing while the input field is focussed
$('#addContactForm').on('keyup change', function () {
if (!$(document.activeElement).is('input')) return; //add this line

Why is my .blur() code only working on second blur?

I have an input, when the user enters something, my script sends the info over to a php script, which returns whether or not the entered text can be used.
If the text can not be used, it disables the submit button and adds a class to the reult text.
The problem have is strange, the ajax works, the result is returned, but the button disabling and adding of the class doesn't happen unless you focus and blur the input a second time.
Here is my code:
$('#alias').blur(function() {
if ($('#alias').val()) {
var aliascheck = $('#alias').val();
$(".aliascheck").load('checkalias.php?alias='+aliascheck);
var result = $('.aliascheck').text();
if (result.indexOf("Taken") != -1) {
$('#shorten').attr("disabled","disabled");
$('.aliascheck').addClass('error');
} else {
$('#shorten').removeAttr("disabled");
$('.aliascheck').removeClass('error');
}
}
});
The code is live here: http://markhenderson.ws/dev/tmtmu/
To replicate the "taken" event, enter "taken" as the alias. Any thing else will return available.
Does anyone know why this is happening?
Thanks

You need to put the code after the .load call into a callback function of the async call.
Something like:
$('#alias').blur(function() {
if ($('#alias').val()) {
var aliascheck = $('#alias').val();
$(".aliascheck").load('checkalias.php?alias='+aliascheck, function() {
var result = $('.aliascheck').text();
if (result.indexOf("Taken") != -1) {
$('#shorten').attr("disabled","disabled");
$('.aliascheck').addClass('error');
} else {
$('#shorten').removeAttr("disabled");
$('.aliascheck').removeClass('error');
}
});
}
});

Disabling/enabling a button based on multiple other controls using Javascript/jQuery

I have a bunch of controls:
When a user clicks the Generate button, a function uses all of the values from the other controls to generate a string which is then put in the Tag text box.
All of the other controls can have a value of null or empty string. The requirement is that if ANY of the controls have no user entered value then the Generate button is disabled. Once ALL the controls have a valid value, then the Generate button is enabled.
What is the best way to perform this using Javascript/jQuery?

This can be further optimized, but should get you started:
var pass = true;
$('select, input').each(function(){
if ( ! ( $(this).val() || $(this).find(':selected').val() ) ) {
$(this).focus();
pass = false;
return false;
}
});
if (pass) {
// run your generate function
}
http://jsfiddle.net/ZUg4Z/
Note: Don't use this: if ( ! ( $(this).val() || $(this).find(':selected').val() ) ).
It's just for illustration purposes.

This code assumes that all the form fields have a default value of the empty string.
$('selector_for_the_parent_form')
.bind('focus blur click change', function(e){
var
$generate = $('selector_for_the_generate_button');
$generate.removeAttr('disabled');
$(this)
.find('input[type=text], select')
.each(function(index, elem){
if (!$(elem).val()) {
$generate.attr('disabled', 'disabled');
}
});
});
Basically, whenever an event bubbles up to the form that might have affected whether the generate button ought to be displayed, test whether any inputs have empty values. If any do, then disable the button.
Disclaimer: I have not tested the code above, just wrote it in one pass.

If you want the Generate button to be enabled as soon as the user presses a key, then you probably want to capture the keypress event on each input and the change event on each select box. The handlers could all point to one method that enables/disables the Generate button.
function updateGenerateButton() {
if (isAnyInputEmpty()) {
$("#generateButton").attr("disabled", "disabled");
} else {
$("#generateButton").removeAttr("disabled");
}
}
function isAnyInputEmpty() {
var isEmpty = false;
$("#input1, #input2, #select1, #select2").each(function() {
if ($(this).val().length <= 0) {
isEmpty = true;
}
});
return isEmpty;
}
$("#input1, #input2").keypress(updateGenerateButton);
$("#select1, #select2").change(updateGenerateButton);
The above assumes that your input tags have "id" attributes like input1 and select2.

Onsubmit validate change background requried fields?

Anyone know of a good tutorial/method of using Javascript to, onSubmit, change the background color of all empty fields with class="required" ?

Something like this should do the trick, but it's difficult to know exactly what you're looking for without you posting more details:
document.getElementById("myForm").onsubmit = function() {
var fields = this.getElementsByClassName("required"),
sendForm = true;
for(var i = 0; i < fields.length; i++) {
if(!fields[i].value) {
fields[i].style.backgroundColor = "#ff0000";
sendForm = false;
}
else {
//Else block added due to comments about returning colour to normal
fields[i].style.backgroundColor = "#fff";
}
}
if(!sendForm) {
return false;
}
}
This attaches a listener to the onsubmit event of the form with id "myForm". It then gets all elements within that form with a class of "required" (note that getElementsByClassName is not supported in older versions of IE, so you may want to look into alternatives there), loops through that collection, checks the value of each, and changes the background colour if it finds any empty ones. If there are any empty ones, it prevents the form from being submitted.
Here's a working example.

Perhaps something like this:
$(document).ready(function () {
$('form').submit(function () {
$('input, textarea, select', this).foreach(function () {
if ($(this).val() == '') {
$(this).addClass('required');
}
});
});
});

I quickly became a fan of jQuery. The documentation is amazing.
http://docs.jquery.com/Downloading_jQuery
if You decide to give the library a try, then here is your code:
//on DOM ready event
$(document).ready(
// register a 'submit' event for your form
$("#formId").submit(function(event){
// clear the required fields if this is the second time the user is submitting the form
$('.required', this).removeClass("required");
// snag every field of type 'input'.
// filter them, keeping inputs with a '' value
// add the class 'required' to the blank inputs.
$('input', this).filter( function( index ){
var keepMe = false;
if(this.val() == ''){
keepMe = true;
}
return keepMe;
}).addClass("required");
if($(".required", this).length > 0){
event.preventDefault();
}
});
);