Develop Reference

Javascript checking if username already exists(duplicate)

I created a function that checks if the username already exists in the data list, but alert shows every time even if the username isn't in duplicate data list.
<form onsubmit="return validation()">
<table>
<tr>
<td>Username:</td>
<td><input type="text" id="user" name="user"></td>
<datalist id="list">
<option value="Tilen">
<option value="Marko">
<option value="Teja">
<option value="Tisa">
<option value="Rok">
<option value="Luka">
<option value="Mojca">
</datalist>
</tr>
</table>
</form>
<script>
function validation(){
var user = document.getElementById("user");
if(user.value.length <= 20 && user.value.length >= 3){
}
else{
alert("Username has to be between 3-20 characters.")
}
//duplication data list
var user = document.getElementById("user");
if(user.value == list.value){
}
else{
alert("Username already exists.")
}
}
</script>

You can get all the options using querySelector, iterate over them and compare then with user.value. Also you need list="polje_imen" in the input element.
function validacija() {
let user = document.getElementById('user');
let listOptions = document.querySelectorAll("#list option");
if (user.value.length <= 20 && user.value.length >= 3) {} else {
alert("Username has to be between 3-20 characters.")
}
for (let i = 0; i < listOptions.length; i++) {
if (listOptions[i].value === user.value) {
alert('The name already exist')
}
}
return false;
}
<form onsubmit="return validacija()">
<table>
<tr>
<td>Username:</td>
<td><input type="text" id="user" name="user" list="list"></td>
<datalist id="list">
<option value="Tilen">
<option value="Marko">
<option value="Teja">
<option value="Tisa">
<option value="Rok">
<option value="Luka">
<option value="Mojca">
</datalist>
</tr>
</table>
</form>
Edit: If you do not want to show the datalist, just use javascript.
function validacija() {
let user = document.getElementById('user');
let listNames = ["Tilen","Marko","Teja","Tisa","Rok","Luka","Mojca"];
if (user.value.length <= 20 && user.value.length >= 3) {} else {
alert("Username has to be between 3-20 characters.")
}
for (let i = 0; i < listNames.length; i++) {
if (listNames[i] === user.value) {
alert('The name already exist')
}
}
return false;
}
<form onsubmit="return validacija()">
<table>
<tr>
<td>Username:</td>
<td><input type="text" id="user" name="user"></td>
</tr>
</table>
</form>

Firstly, I don't think you're binding to the input on the datalist correctly. You can actually use the datalist as an autocomplete for the input if you simply change your input to look like this:
<input type="text" id="upor_ime" name="upor_ime" list="polje_imen">
If you have that in there, it becomes much more obvious if they choose a value that is not in the list or not from a visual perspective. Now when it comes to validating it in javascript, if you still want to take it that far, you're going to have to break out your list of possible names into an array so you can check to see if the string you're entering in the input exists in the array of strings. Because you're trying to compare an array of strings to a string, using the == operator in an if statement will not work. Here's a possible solution:
<form onsubmit="return validacija()">
<table>
<tr>
<td>Uporabniško ime:</td>
<td><input type="text" id="upor_ime" name="upor_ime" list="polje_imen"></td>
<datalist id="polje_imen"></datalist>
</tr>
</table>
</form>
<script>
var names = ["Tilen", "Marko", "Teja", "Tisa", "Rok", "Luka", "Mojca"];
var options = "";
for (let name of names) {
options += "<option value='" + name + "'>";
}
document.getElementById("polje_imen").innerHTML = options;
function validacija(){
var upor_ime = document.getElementById("upor_ime");
if(upor_ime.value.length > 20 || upor_ime.value.length < 3){
alert("Uporabniško ime mora imeti med 3-20 znakov.")
return;
}
//duplication data list
var polje_imen = document.getElementById("polje_imen");
if(names.includes(upor_ime.value)) {
alert("Uporabniško ime že obstaja.");
return;
} else{
// success
}
}
</script>
Here is a JSFiddle: http://jsfiddle.net/4f1hztr2/
Edit: I also changed around some of your if statement logic so that if the length of the item wasn't right it didn't continue executing the rest of the code.

jquery to submit form only after condition is valid and display alert if not

I have this jQuery code. I want to find out what is causing the alertify.error() to displayed as many times as it executes foreach loop to find the sum of the value of text box. Can somebody help me here.
$(document).ready(function() {
$("form").submit(function(e) {
e.preventDefault();
var sum = claculateTotal();
if ($("#TotalWeigh").val() != sum) {
alertify.error('Total weigh should be equal to the sum of weigh of all leaf quality.');
return false;
} else {
this.submit();
}
});
function claculateTotal() {
var sum = 0;
$('.leafWeigh').each(function() {
sum += Number($(this).val());
});
return sum;
}
});
And i have my html code for text boxes as below:
for (int i = 0; i < Model.boughtWeighingModel.Count(); i++)
{
<tr>
<td>
#Html.TextBoxFor(model => Model.boughtWeighingModel[i].LeafQaualityWeight,
new { #class = "form-control leafWeigh" })
</td>
</tr>
}

Why do you really need a <form> element?
HTML
<input name="" />
<button id="submit">Submit</button>
JS
submit.onclick = function(){
// validate and do some ajax...
}

Displaying range validator error message on html input

I have an input type =text in html and i have this js code in js file to show error message
var $form = $("#myid"),
$errorMsg = $("<span id='myerrormessagespan' class='error' style='color:red;'>*</span>");
var toReturn = 0;
$("input", $form).each(function () {
if ($(this).val() == "") {
if (!$(this).data("error")) {
$(this).data("error", $errorMsg.clone().insertAfter($(this)));
}
toReturn = 1;
}
else {
if ($(this).data("error")) {
$(this).data("error").remove();
$(this).removeData("error");
}
}
});
I am trying to convert this code to make range validator on input type=text field .dispalying only 5 digits in the textbox, but i couldn't achieve . Is there any easy way to do this ?
Thanks

Consider using the jQuery validation plugin instead, especially the rangelength method for your case. However, if you want to stick to the original code without using any library then I suggest you try the code below for example:
HTML:
<form id="myid" name="myid" method="post" action="/">name :
<input type="text" name="name" id="name" />age :
<input type="text" name="age" id="age" />
<input type="submit" id="submit" name="submit" value="Save" />
</form>
jQuery:
var $form = $("#myid"),
$errorMsg = $("<span id='myerrormessagespan' class='error' style='color:red;'>*</span>");
$("#submit").on("click", function () {
var toReturn = true;
$("input", $form).each(function () {
var value = $(this).val();
if((!$.trim(this.value).length) || (value.length > 5)) {
if (!$(this).data("error")) {
$(this).data("error", $errorMsg.clone().insertAfter($(this)));
}
toReturn = false;
}
else {
if ($(this).data("error")) {
$(this).data("error").remove();
$(this).removeData("error");
}
}
});
return toReturn;
});
Working JSFiddle Demo

Textbox value compare before submitting

I want to let my two textboxes be checked before those get submitted.
like
if textbox1 >= textbox2 submit
else show errorlabel and dont submit.
How can i do this?

Provide your onclick handler's implementation to extract the value of the two text boxes, then parse them as an int.
function submitForm() {
var first = parseInt(document.getElementById("first"), 0);
var second = parseInt(document.getElementById("second"), 0);
if(first >= second) {
// ...
return true;
} else {
var hiddenTextBox = document.getElementById("error");
hiddenTextBox.style.visibility = "visible";
return false;
}
}
This assumes you have two elements with id="first" and id="second" respectively, and a hidden element with id="error"

Try it like,
$('#submitId').on('click',function(){
if $('#textbox1').val() < $('#textbox2').val()){
$('#erroLabel').show(); // showing error label
return false; // to prevent submitting form
}
});

You can make function in javascript,
<script type="text/javascript">
function checkValues()
{
var searchtext1 = document.getElementById("textbox1").value;
if(searchtext1=='')
{
alert('Enter any character');
return false;
}
var searchtext2 = document.getElementById("textbox2").value;
if(searchtext2=='')
{
alert('Enter any character');
return false;
}
}
</script>
and then in html form
<form method='GET' onSubmit="return checkValues();">
<input type="text" id= "textbox1" name="textbox1" class='textbox' >
<input type="text" id= "textbox2" name="textbox2" class='textbox' >
<input type="submit" id='submit' value="Search" class ='button' >
</form>

validation of input text field in html using javascript

<script type='text/javascript'>
function required()
{
var empt = document.forms["form1"]["Name"].value;
if (empt == "")
{
alert("Please input a Value");
return false;
}
}
</script>
<form name="form1" method="" action="">
<input type="text" name="name" value="Name"/><br />
<input type="text" name="address line1" value="Address Line 1"/><br />
I have more than one input text field, each having their default value. Before I submit the form I have to verify whether all fields are filled. So far i got the javascript to check for null since different text boxes have different default value. How can I write a javascript to verify that user has entered data? I mean, the script must identify that input data is other than default and null.

If you are not using jQuery then I would simply write a validation method that you can be fired when the form is submitted. The method can validate the text fields to make sure that they are not empty or the default value. The method will return a bool value and if it is false you can fire off your alert and assign classes to highlight the fields that did not pass validation.
HTML:
<form name="form1" method="" action="" onsubmit="return validateForm(this)">
<input type="text" name="name" value="Name"/><br />
<input type="text" name="addressLine01" value="Address Line 1"/><br />
<input type="submit"/>
</form>
JavaScript:
function validateForm(form) {
var nameField = form.name;
var addressLine01 = form.addressLine01;
if (isNotEmpty(nameField)) {
if(isNotEmpty(addressLine01)) {
return true;
{
{
return false;
}
function isNotEmpty(field) {
var fieldData = field.value;
if (fieldData.length == 0 || fieldData == "" || fieldData == fieldData) {
field.className = "FieldError"; //Classs to highlight error
alert("Please correct the errors in order to continue.");
return false;
} else {
field.className = "FieldOk"; //Resets field back to default
return true; //Submits form
}
}
The validateForm method assigns the elements you want to validate and then in this case calls the isNotEmpty method to validate if the field is empty or has not been changed from the default value. it continuously calls the inNotEmpty method until it returns a value of true or if the conditional fails for that field it will return false.
Give this a shot and let me know if it helps or if you have any questions. of course you can write additional custom methods to validate numbers only, email address, valid URL, etc.
If you use jQuery at all I would look into trying out the jQuery Validation plug-in. I have been using it for my last few projects and it is pretty nice. Check it out if you get a chance. http://docs.jquery.com/Plugins/Validation

<form name="myForm" id="myForm" method="post" onsubmit="return validateForm();">
First Name: <input type="text" id="name" /> <br />
<span id="nameErrMsg" class="error"></span> <br />
<!-- ... all your other stuff ... -->
</form>
<p>
1.word should be atleast 5 letter<br>
2.No space should be encountered<br>
3.No numbers and special characters allowed<br>
4.letters can be repeated upto 3(eg: aa is allowed aaa is not allowed)
</p>
<button id="validateTestButton" value="Validate now" onclick="validateForm();">Validate now</button>
validateForm = function () {
return checkName();
}
function checkName() {
var x = document.myForm;
var input = x.name.value;
var errMsgHolder = document.getElementById('nameErrMsg');
if (input.length < 5) {
errMsgHolder.innerHTML =
'Please enter a name with at least 5 letters';
return false;
} else if (!(/^\S{3,}$/.test(input))) {
errMsgHolder.innerHTML =
'Name cannot contain whitespace';
return false;
}else if(!(/^[a-zA-Z]+$/.test(input)))
{
errMsgHolder.innerHTML=
'Only alphabets allowed'
}
else if(!(/^(?:(\w)(?!\1\1))+$/.test(input)))
{
errMsgHolder.innerHTML=
'per 3 alphabets allowed'
}
else {
errMsgHolder.innerHTML = '';
return undefined;
}
}
.error {
color: #E00000;
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Validation</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript">
var tags = document.getElementsByTagName("input");
var radiotags = document.getElementsByName("gender");
var compareValidator = ['compare'];
var formtag = document.getElementsByTagName("form");
function validation(){
for(var i=0;i<tags.length;i++){
var tagid = tags[i].id;
var tagval = tags[i].value;
var tagtit = tags[i].title;
var tagclass = tags[i].className;
//Validation for Textbox Start
if(tags[i].type == "text"){
if(tagval == "" || tagval == null){
var lbl = $(tags[i]).prev().text();
lbl = lbl.replace(/ : /g,'')
//alert("Please Enter "+lbl);
$(".span"+tagid).remove();
$("#"+tagid).after("<span style='color:red;' class='span"+tagid+"'>Please Enter "+lbl+"</span>");
$("#"+tagid).focus();
//return false;
}
else if(tagval != "" || tagval != null){
$(".span"+tagid).remove();
}
//Validation for compare text in two text boxes Start
//put two tags with same class name and put class name in compareValidator.
for(var j=0;j<compareValidator.length;j++){
if((tagval != "") && (tagclass.indexOf(compareValidator[j]) != -1)){
if(($('.'+compareValidator[j]).first().val()) != ($('.'+compareValidator[j]).last().val())){
$("."+compareValidator[j]+":last").after("<span style='color:red;' class='span"+tagid+"'>Invalid Text</span>");
$("span").prev("span").remove();
$("."+compareValidator[j]+":last").focus();
//return false;
}
}
}
//Validation for compare text in two text boxes End
//Validation for Email Start
if((tagval != "") && (tagclass.indexOf('email') != -1)){
//enter class = email where you want to use email validator
var reg = /^\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*$/
if (reg.test(tagval)){
$(".span"+tagid).remove();
return true;
}
else{
$(".span"+tagid).remove();
$("#"+tagid).after("<span style='color:red;' class='span"+tagid+"'>Email is Invalid</span>");
$("#"+tagid).focus();
return false;
}
}
//Validation for Email End
}
//Validation for Textbox End
//Validation for Radio Start
else if(tags[i].type == "radio"){
//enter class = gender where you want to use gender validator
if((radiotags[0].checked == false) && (radiotags[1].checked == false)){
$(".span"+tagid).remove();
//$("#"+tagid").after("<span style='color:red;' class='span"+tagid+"'>Please Select Your Gender </span>");
$(".gender:last").next().after("<span style='color:red;' class='span"+tagid+"'> Please Select Your Gender</span>");
$("#"+tagid).focus();
i += 1;
}
else{
$(".span"+tagid).remove();
}
}
//Validation for Radio End
else{
}
}
//return false;
}
function Validate(){
if(!validation()){
return false;
}
return true;
}
function onloadevents(){
tags[tags.length -1].onclick = function(){
//return Validate();
}
for(var j=0;j<formtag.length;j++){
formtag[j].onsubmit = function(){
return Validate();
}
}
for(var i=0;i<tags.length;i++){
var tagid = tags[i].id;
var tagval = tags[i].value;
var tagtit = tags[i].title;
var tagclass = tags[i].className;
if((tags[i].type == "text") && (tagclass.indexOf('numeric') != -1)){
//enter class = numeric where you want to use numeric validator
document.getElementById(tagid).onkeypress = function(){
numeric(event);
}
}
}
}
function numeric(event){
var KeyBoardCode = (event.which) ? event.which : event.keyCode;
if (KeyBoardCode > 31 && (KeyBoardCode < 48 || KeyBoardCode > 57)){
event.preventDefault();
$(".spannum").remove();
//$(".numeric").after("<span class='spannum'>Numeric Keys Please</span>");
//$(".numeric").focus();
return false;
}
$(".spannum").remove();
return true;
}
if (document.addEventListener) {
document.addEventListener("DOMContentLoaded", onloadevents, false);
}
//window.onload = onloadevents;
</script>
</head>
<body>
<form method="post">
<label for="fname">Test 1 : </label><input type="text" title="Test 1" id="fname" class="form1"><br>
<label for="fname1">Test 2 : </label><input type="text" title="Test 2" id="fname1" class="form1 compare"><br>
<label for="fname2">Test 3 : </label><input type="text" title="Test 3" id="fname2" class="form1 compare"><br>
<label for="gender">Gender : </label>
<input type="radio" title="Male" id="fname3" class="gender" name="gender" value="Male"><label for="gender">Male</label>
<input type="radio" title="Female" id="fname4" class="gender" name="gender" value="Female"><label for="gender">Female</label><br>
<label for="fname5">Mobile : </label><input type="text" title="Mobile" id="fname5" class="numeric"><br>
<label for="fname6">Email : </label><input type="text" title="Email" id="fname6" class="email"><br>
<input type="submit" id="sub" value="Submit">
</form>
</body>
</html>

function hasValue( val ) { // Return true if text input is valid/ not-empty
return val.replace(/\s+/, '').length; // boolean
}
For multiple elements you can pass inside your input elements loop their value into that function argument.
If a user inserted one or more spaces, thanks to the regex s+ the function will return false.

<pre><form name="myform" action="saveNew" method="post" enctype="multipart/form-data">
<input type="text" id="name" name="name" />
<input type="submit"/>
</form></pre>
<script language="JavaScript" type="text/javascript">
var frmvalidator = new Validator("myform");
frmvalidator.EnableFocusOnError(false);
frmvalidator.EnableMsgsTogether();
frmvalidator.addValidation("name","req","Plese Enter Name");
</script>
before using above code you have to add the gen_validatorv31.js js file

For flexibility and other places you might want to validated. You can use the following function.
`function validateOnlyTextField(element) {
var str = element.value;
if(!(/^[a-zA-Z, ]+$/.test(str))){
// console.log('String contain number characters');
str = str.substr(0, str.length -1);
element.value = str;
}
}`
Then on your html section use the following event.
<input type="text" id="names" onkeyup="validateOnlyTextField(this)" />
You can always reuse the function.