Develop Reference

Submit form after unbinding

$("#qwerq").submit(function (e){
e.preventDefault();
var check=0;
if($("#firstName").val() == "") {
check=1;
}
if(check!=1){
$("#qwerq").unbind("submit") ;
$("#qwerq").submit();
//$("#qwerq").trigger('submit', [true]);
}
});
When the form is having id="qwerq" is as per needs and the submit gets unbinded, the form does not submit on its own.
I have tried using .submit() and .trigger("submit"). I have to manually click on submit again.
What should I add so that I don't have to click again?

Instead of unbinding the events, why won't you just prevent submitting only on error?
if(check === 1) return false;
return false in jQuery's event handler means preventDefault and stopPropagation.

I think you were trying to submit a form on a button click.
Then you need to make some changes in your code:
Provide an id to your form and change button type="button" (instead of "submit"):
<form id="form_1" action="yourserverpagename.php" method="post">
<input id="firstName" type="text" value="" />
<input id="qwerq" type="button" value="Send" />
</form>
Now your script should like below:
<script>
$("#qwerq").click(function (e) {
e.preventDefault();
var check = 0;
if ($("#firstName").val() == "") {
check = 1;
}
if (check != 1) {
//-- here is the way to submit the form using form id --
$('#form_1').submit();
}
});
</script>

Insert missing letter javascript game

I'm making a language learning game with javascript. I want the user to be able to write the missing letter and the results to be validated through javascript if they are right or wrong.
<form>
De<input id="letterone" type="text" name="latter" pattern="[A-Za-z]{1}">
ign<input id="lettertwo" type="text" name="latter" pattern="[A-Za-z]{1}">r
<input type="submit">
</form>
My javascript code.
if ((getElementById('letterone')==='s') && (getElementById('lettertwo')==='e')) {
alert('Correct');
}else{
alert('Wrong');
}

There are number of errors on your code :
No 'document' before getElementById
No 'value' after the object
No click handler
Incorrect id while accessing the object
Using input type=submit causes an unwanted page refresh as Useless Code comments below.
document.getElementById('submit').addEventListener('click', function() {
if ((document.getElementById('latterone').value==='s') && (document.getElementById('lattertwo').value==='e')) {
alert('Correct');
}else{
alert('Wrong');
}
});
<form>
De<input type="text" id="latterone" pattern="[A-Za-z]{1}">
ign<input type="text" id="lattertwo" pattern="[A-Za-z]{1}">r
<input type="button" id="submit" value="Submit">
</form>

var lOne = document.getElementById('letterone').value; // get the value of the first input
var lTwo = document.getElementById('lettertwo').value; // get the value of the second
if (lOne === 's') && lTwo === 'e') {
alert('Correct');
}else{
alert('Wrong');
}

Check if every elemnt from a form is filled JQUERY

I have a form with all types of form elemnts and I have a code that should run through every single one of the elemnts and check their value after the submit button is clicked. Unfortunatelly, this code doesn't work completely. What I mean is that if I don't enter any value in the input, it will print the message, but if I enter some text in it, we go to the else statement, without checking the other.
Could somebody tell me why?
if($('form.registration-form :input').val() == '')
{
// Print Error Message
}
else
{
// Do something else
}

You can use filter method for this:
var emptyElements = $('form.registration-form :input').filter( function() {
return this.value === '';
});
if( emptyElements.length === 0 ) {
// all IS filled in
} else {
// all is NOT filled in
}
$('#submit').click(function(){
var emptyElements = $('form.registration-form :input').filter( function() {
return this.value === '';
});
if( emptyElements.length === 0 ) {
alert('All Filled');
} else {
alert('1 or more not filled')
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form action="" class="registration-form">
<input type="text">
<input type="text">
<input type="text">
<input type="text">
<input type="submit" id="submit" value="Check">
</form>

Attempting to prevent submitting empty form

I have a form in my HTML document, and it only has a "text" input, and a submit button.
I also have JavaScript that checks if the field is empty and returns true or false.
JSFiddle: http://jsfiddle.net/HBZ7t/
HTML:
<form onsubmit="checkNull();" method="post">
<input type="text" id="field">
<input type="submit">
</form>
JavaScript
function checkNull() {
var field = document.getElementById("field");
if(field.value !== "") {
return true;
}
return false;
}
However, the form can be submitted even if the text field is empty... Any suggestions?

You are doing nearly everything right, you just need to return the value from the function to the handler:
<form onsubmit="return checkNull();" method="post">
// -------------^^^^^^

In JavaScript you can use double exclamation points to check for lots of non-valid settings:
function checkNull() {
var field = document.getElementById("field");
if(!!field.value) {
return true;
} else {
return false;
};

FIDDLE
JS
var form=document.getElementById("form");
form.onsubmit=function(){
var field = document.getElementById("field");
if (field.value !== "") {
return true;
}
return false;
};
HTML
<form id="form" method="post">
<input type="text" id="field">
<input type="submit">
</form>

you can use event.preventDefault() to cancel a event, see mozila doc here
Also, check the very nice jQuery submit function and samples here
Check this sample: http://jsfiddle.net/HBZ7t/5/
$( "#target" ).submit(function( event ) {
if($('#field').val()=='')
{
alert('cancel event');
event.preventDefault();
}
});

Using jQuery to prevent form submission when input fields are empty

The solution should be pretty straightforward. I'm trying to prevent the form from submitting properly when no value is found within the input boxes. Here's my JSFiddle: http://jsfiddle.net/nArYa/7/
//Markup
<form action="" method="post" name="form" id="form">
<input type="text" placeholder="Your email*" name="email" id="email">
<input type="text" placeholder="Your name*" autocomplete=off name="name" id="user_name"
<button type="submit" id="signup" value="Sign me up!">Sign Up</button>
</form>
//jQuery
if ($.trim($("#email, #user_name").val()) === "") {
$('#form').submit(function(e) {
e.preventDefault();
alert('you did not fill out one of the fields');
})
}
As you can see in the JSFiddle, the problem is that when I type something into both fields, the alert box STILL pops up. I'm having a hard time figuring out why. Is there something wrong within my
if($.trim($"#email, #user_name").val()) === "") ?

Two things, #1 the check for empty fields should happen on every attempt of submit, #2 you need to check each field individually
$('#form').submit(function() {
if ($.trim($("#email").val()) === "" || $.trim($("#user_name").val()) === "") {
alert('you did not fill out one of the fields');
return false;
}
});
Updated fiddle

Your check occurs on page load. You need to check the field when the form is submitted.
$('#form').submit(function(e) {
if ($.trim($("#email, #user_name").val()) === "") {
e.preventDefault();
alert('you did not fill out one of the fields');
}
});

HTML5: use required in input tag
A boolean attribute.
Input field must be filled out before submitting the form.
Works with text, search, url, tel, email, password, date pickers, number, checkbox, radio, and file.
<input required type='text'...>
w3schools hint

I guess that this will help:
$('#form').submit(function(e) {
e.preventDefault();
$("#email, #user_name").each(function(){
if($.trim(this.value) == ""){
alert('you did not fill out one of the fields');
} else {
// Submit
}
})
})

Put your if statement inside the callback:
$('#form').submit(function(e) {
if ($.trim($("#email").val()) === "" || $.trim($("#user_name").val())) {
e.preventDefault();
alert('you did not fill out one of the fields');
//You can return false here as well
}
});