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ValidateForm How to validate and show text when submit button was clicked in JavaScript

I would like to show tick simple when the field is filled correctly, and show error message when it is not filled on each field.
I tried to make the code which using function validateForm, but it did not work. How do I fix the code? Please teach me where to fix.
Here is my html code
<form>
<div class="Form-Item">
<p class="Form-Item-Label"><span class="Form-Item-Label-Required">Required</span>Name</p>
<input type="text"id="name">
</div>
<div class="Form-Item">
<p class="Form-Item-Label"><span class="Form-Item-Label-Required" >Required</span>Number</p>
<input type="text" id="number">
</div>
<div class="Form-Item">
<p class="Form-Item-Label"><span class="Form-Item-Label-Required">Required</span>Mail address</p>
<input type="email">
</div>
<div class="Form-Item">
<p class="Form-Item-Label isMsg"><span class="Form-Item-Label-Required">Required</span>Message</p>
<textarea id="text"></textarea>
</div>
<input type="submit" value="submit">
<p id="log"></p>
</form>
Here is my JavaScript code
function validateForm(e) {
if (typeof e == 'undefined') e = window.event;
var name = U.$('name');
var number = U.$('number');
var email = U.$('email');
var text = U.$('text');
var error = false;
if (/^[A-Z \.\-']{2,20}$/i.test(name.value)) {
removeErrorMessage('name');
addCorrectMessage('name', '✔');
} else {
addErrorMessage('name', 'Please enter your name.');
error = true;
}
if (/\d{3}[ \-\.]?\d{3}[ \-\.]?\d{4}/.test(number.value)) {
removeErrorMessage('number');
addCorrectMessage('number', '✔');
} else {
addErrorMessage('number', 'Please enter your phone number.');
error = true;
}
if (/^[\w.-]+#[\w.-]+\.[A-Za-z]{2,6}$/.test(email.value)) {
removeErrorMessage('email');
addCorrectMessage('email', '✔');
} else {
addErrorMessage('email', 'Please enter your email address.');
error = true;
}
if (/^[A-Z \.\-']{2,20}$/i.test(text.value)) {
removeErrorMessage('text');
addCorrectMessage('text', '✔');
} else {
addErrorMessage('text', 'Please enter your enquiry.');
error = true;
}
if (error) {
if (e.preventDefault) {
e.preventDefault();
} else {
e.returnValue = false;
}
return false;
}
}
function addErrorMessage(id, msg) {
'use strict';
var elem = document.getElementById(id);
var newId = id + 'Error';
var span = document.getElementById(newId);
if (span) {
span.firstChild.value = msg;
} else {
span = document.createElement('span');
span.id = newId;
span.className = 'error';
span.appendChild(document.createTextNode(msg));
elem.parentNode.appendChild(span);
elem.previousSibling.className = 'error';
}
}
function addCorrectMessage(id, msg) {
'use strict';
var elem = document.getElementById(id);
var newId = id + 'Correct';
var span = document.getElementById(newId);
if (span) {
span.firstChild.value = msg;
} else {
span = document.createElement('span');
span.id = newId;
span.className = 'Correct';
span.appendChild(document.createTextNode(msg));
elem.parentNode.appendChild(span);
elem.previousSibling.className = 'Correct';
}
}
function removeErrorMessage(id) {
'use strict';
var span = document.getElementById(id + 'Error');
if (span) {
span.previousSibling.previousSibling.className = null;
span.parentNode.removeChild(span);
}
}
function removeCorrectMessage(id) {
'use strict';
var span = document.getElementById(id + 'Correct');
if (span) {
span.previousSibling.previousSibling.className = null;
span.parentNode.removeChild(span);
}
}

Using jQuery, you can use the .submit() event on a form element to conduct your own validation, note that you will have to preventDefault() to prevent the form submitting.
$("#myform").submit((e) => {
e.preventDefault(e);
// Validate name.
const name = $("#name").val();
if (name.length === 0) {
alert("Please provide a name!");
return;
}
alert("Success!");
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form id="myform">
<input type="text" id="name" placeholder="John Doe" />
<button type="submit">Submit</button>
</form>

which npm package do u use to validate ur data?.
If u use "validator" (link: https://www.npmjs.com/package/validator)
You can check if the field is filled correctly and send a check mark to the user.
for example if u wanted to check if data is an email
const validator = require("validator");
validator.isEmail('foo#bar.com');
if u want to see more about the options for the field just check the npm package page

Modern Browser support the Constraint Validation API which provides localized error messages.
Using this you can easily perform validation during basic events. For example:
// this will prevent the form from submit and print the keys and values to the console
document.getElementById("myForm").onsubmit = function(event) {
if (this.checkValidity()) {
[...new FormData(this).entries()].forEach(([key, value]) => console.log(`${key}: ${value}`);
event.preventDefault();
return false;
}
}
Would print all fields which would've been submitted to the console.
Or on an input field:
<input type="text" pattern="(foo|bar)" required oninput="this.parentNode.classList.toggle('valid', this.checkValidity());">
Will add the css class "valid" to the input field parent, if the value is foo or bar.
.valid {
border: 1px solid green;
}
.valid::after {
content: '✅'
}
<form oninput="this.querySelector('#submitButton').disabled = !this.checkValidity();" onsubmit="event.preventDefault(); console.log('Submit prevented but the form seems to be valid.'); return false;">
<fieldset>
<label for="newslettermail">E-Mail</label>
<!-- you could also define a more specific pattern on the email input since email would allow foo#bar as valid mail -->
<input type="email" id="newslettermail" oninput="this.parentNode.classList.toggle('valid', this.checkValidity());" required>
</fieldset>
<fieldset>
<input type="checkbox" id="newsletterAcceptTos" oninput="this.parentNode.classList.toggle('valid', this.checkValidity());" required>
<label for="newsletterAcceptTos">I accept the Terms of Service</label>
</fieldset>
<fieldset>
<label for="textFieldWithPattern">Enter <strong>foo</strong> or <strong>bar</strong></label>
<input type="text" id="textFieldWithPattern" pattern="^(foo|bar)$" required oninput="this.parentNode.classList.toggle('valid', this.checkValidity());" >
</fieldset>
<button type="submit" id="submitButton" disabled>Submit</button>
<button type="submit">Force submit (will show errors on invalid input)</button>
</form>

How trigger validation on a textbox when a button is pressed?

I've got two text boxes for first and last name. I also have a button to save the data. The button has an event handler where it grabs the data from the fields and posts them with an ajax call to my API, using jquery.
I want validation on my two textboxes (so they can't be left blank), but I don't know how to trigger that when my button is pressed. I am not using the <form> tag for this; I'm doing an ajax call when the button is pressed.

Here is an example which may help you:
$('#save').click(function() {
var errors = [];
var name = $('#name').val();
var vorname = $('#vorname').val();
if (!name) {
errors.push("Name can't be left blank");
}
if (!vorname) {
errors.push("Vorname can't be left blank");
}
if (errors.length == 0) {
console.log('Ajax started');
//put here your ajax function
} else {
for (var i in errors) {
console.log(errors[i]);
}
}
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input placeholder="Name" id="name"><br>
<input placeholder="Vorname" id="vorname"><br>
<button id="save">Save</button>

here is an example using the popular add on jquery validate. https://jqueryvalidation.org/
click the run snippet button below
$(document).ready(function() {
$("#form").validate({
rules: {
"firstname": {
required: true,
},
"lastname": {
required: true,
}
},
messages: {
"firstname": {
required: "Please, enter a first name"
},
"lastname": {
required: "Please, enter a last name"
},
},
submitHandler: function(form) { // for demo
alert('valid form submitted'); // for demo
return false; // for demo
}
});
});
body {
padding: 20px;
}
label {
display: block;
}
input.error {
border: 1px solid red;
}
label.error {
font-weight: normal;
color: red;
}
button {
display: block;
margin-top: 20px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.0/jquery.validate.min.js"></script>
<form id="form" method="post" action="#">
<label for="firstname">First Name</label>
<input type="text" name="firstname" id="firstname" />
<label for="lastname">Last Name</label>
<input type="text" name="lastname" id="lastname" />
<button type="submit">Submit</button>
</form>

Without seeing your code, it is very difficult to guess the correct scenario to provide examples for.
Given the following HTML:
<form>
<input type="text" class="text1">
<input type="text" class="text2">
<button type="button">Send</button>
</form>
You could use this for the jQuery part:
$('button').click(function() {
var txt1 = $(this).siblings('.text1').val();
var txt2 = $(this).siblings('.text2').val();
if (txt1.length && txt2.length) {
// do your ajaxy stuff here
} else {
alert("Imput some friggin' text!");
}
});
$(this) selects the button clicked.
.siblings('.text1') selects the input with class text1 inside the same block as the clicked button.
https://jsfiddle.net/sg1x0c3q/7/

As per my comments I would recommend using a form. But if you want a pure JS solution here you go. (if you want a form based solution just ask)
// convert all textareas into key value pairs (You can change the selector to be specific to your markup)
const createPayload = () => {
return [].slice.call(document.querySelectorAll('textarea')).reduce((collection, textarea) => ({
...collection,
[textarea.name]: textarea.value
}), {})
}
// Compare Object values against values that are not falsy (you could update the filter with a RegExp if you wanted more complicated validation)
const objectHasAllValues = obj => {
return Object.values(obj).length == Object.values(obj).filter(value => value).length
}
// If all key value pairs are not falsy then submit
window.submit = () => {
const payload = createPayload()
if (objectHasAllValues(payload)) {
fetch('/your/api', payload)
}
}
This solution presumes that your API expects a JSON payload. If you are expecting to send form data then you would need to use the formData js api.
This scales and doesn't need jQuery :)
Working example here https://jsfiddle.net/stwilz/dxg29mkj/28/

I want validation on my two textboxes (so they can't be left blank), but I don't know how to trigger that when my button is pressed. I am not using the <form> tag for this; I'm doing an ajax call when the button is pressed.
Answer to form validation. I assume that First name and Last name can only contain alphabets ,i.e., only a-z and A-Z.
//This function will trim extra whitespaces form input.
function trimInput(element){
$(element).val($(element).val().replace(/\s+/g, " ").trim());
}
//This function will check if the name is empty
function isEmpty(s){
var valid = /\S+/.test(s);
return valid;
}
//This function will validate name.
function isName(name){
var valid = /^[a-zA-Z]*$/.test(name);
return valid;
}
$('#myForm').submit(function(e){
e.preventDefault();
var fname = $(this).find('input[name="fname"]');
var lname = $(this).find('input[name="lname"]');
var flag = true;
trimInput(fname);
trimInput(lname);
if(isEmpty($(fname).val()) === false || isName($(fname).val()) === false){
alert("First name is invalid.");
flag = false;
}
if(isEmpty($(lname).val()) === false || isName($(lname).val()) === false){
alert("Last name is invalid.");
flag = false;
}
if(flag){
alert("Everything is Okay");
//Code to POST form data goes here...
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form name="myform" id="myForm" method="post" action="#">
<input type="text" name="fname" placeholder="Firstname">
<input type="text" name="lname" placeholder="Last Name">
<input type="submit" name="submit" value="Submit">
</form>
I am not using the <form> tag for this.
Then the code will be like
//This function will trim extra whitespaces form input.
function trimInput(element) {
$(element).val($(element).val().replace(/\s+/g, " ").trim());
}
//This function will check if the name is empty
function isEmpty(s) {
var valid = /\S+/.test(s);
return valid;
}
//This function will validate name.
function isName(name) {
var valid = /^[a-zA-Z]*$/.test(name);
return valid;
}
$('#submit').click(function() {
var fname = $('#fname');
var lname = $('#lname');
var flag = true;
trimInput(fname);
trimInput(lname);
if (isEmpty($(fname).val()) === false || isName($(fname).val()) === false) {
alert("First name is invalid.");
flag = false;
}
if (isEmpty($(lname).val()) === false || isName($(lname).val()) === false) {
alert("Last name is invalid.");
flag = false;
}
if (flag) {
alert("Everything is Okay");
//Code to POST form data goes here...
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="fname" name="fname" placeholder="Firstname">
<input type="text" id="lname" name="lname" placeholder="Last Name">
<button type="button" id="submit" name="submit">Submit</button>
Check the code on jsFiddle.
Hope this will be helpful.

how to give "same as the above" in form entries

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<form method="POST" class="form-group">
<label>First Name</label><input type="text" name="FName" class="form-control">
<label>Last Name</label><input type="text" name="LName" class="form-control"><br>
<label>I am Ready</label><input type="checkbox" name="ch"><br><br>
<label>Address</label><input type="text" name="Address" class="form-control">
</form><br><br>
<form method="POST" class="form-group">
<label>Same as Above</label><input type="checkbox" name="chd"><br><br>
<label>First Name</label><input type="text" name="FName" class="form-control">
<label>Last Name</label><input type="text" name="LName" class="form-control"><br>
<label>I am Ready</label><input type="checkbox" name="ch"><br><br>
<label>Address</label><input type="text" name="Address" class="form-control">
</form>
when we checked the checkbox named 'same as the above' then the second form will have to take same values that are in the first form fields.

you can use jQuery like suppose you have 2 input fields and a checkbox
if you click on checkbox it has to get value from first input and assign it to second like
$(function(){
("#checkbox").click(function(){
if($(this).is(':checked')){
var input1=$("#input1").val();
$("#input2").val(input1);
}
});
});

You need to start listening on proto form fields changes if "same as above" checked and stop listening if unchecked. And when value of any field changes then just proxy values of all proto form fields to surrogate form fields
(function($) {
var $forms = $('form');
var $protoForm = $forms.eq(0);
var $surrogateForm = $forms.eq(1);
var proxyValues = function(name) {
var $fields = $protoForm.find('input');
if (typeof name === 'string') {
$fields = $fields.filter('[name="' + name + '"]');
}
$fields.each(function() {
var field = $surrogateForm.find('[name="' + name + '"]').get(0);
if (field.type === 'checkbox') {
field.checked = this.checked;
} else {
field.value = this.value;
}
});
};
var startValuesProxy = function() {
proxyValues();
$protoForm.on('change.valuesProxy', 'input', function(e) {
proxyValues(e.target.name);
});
};
var stopValuesProxy = function() {
$protoForm.off('.valuesProxy');
};
$surrogateForm.on('change', '[name="chd"]', function(e) {
if (e.target.checked) {
startValuesProxy();
} else {
stopValuesProxy();
}
});
})(jQuery);

1) When You check the checkbox, which would mean you would need to create a hidden field on your Address form, and have the results of the address form fields that you require passed to the hidden fields on the address form.
2) On Checked Box Checked Event. Example
Hope Its Work !!!

In my experience you can just disable the controls - seems to be that way on other sites - then in your submit method - if the checkbox is clicked - send that to the controller and use the 'above' values there too..
$(function() {
$('#chkSameAsAbove').on('change', function() {
var otherControls = $(this).parent().find('input:not(#chkSameAsAbove)');
if($(this).is(':checked')) {
otherControls.prop('disabled', true);
} else {
otherControls.prop('disabled', false);
}
});
});
https://jsfiddle.net/7xv5bv4h/

Get all the inputs in javascript.
Let's say you have two input fields and one checkbox, if checkbox is checked both field will have same value, if not user will enter second value in second input.
so lets try this code:
var input1 = document.getElementById("input1");
if (document.getElementById('checkbox_field_ID').checked) {
$('#input2').append(input1);
}
I hope it helps :)

Send only filled fields via GET

Look at simple form below:
<form method="GET" action="index.php">
<input type="text" name="price_min" >Min
<input type="text" name="price_max" >Max
</form>
When I send form with filled only one field, in my url I get empty values for not filled keys
(ex. index.php?price_min=).
Question:
How to remove empty keys from url?

You can parse serialized string and remove blank values. Then you can use post to necessary api using jQuery.
Sample
JSFiddle
$("#btn").on("click", function() {
var formjson = $("#frmTest").serialize();
var result = formjson.split("&").filter(function(val) {
return val.split("=")[1].length > 0;
}).join("&")
console.log("Serialized String:", formjson);
console.log("Processed String:", result);
// $.get('action.php', formjson, function(response){ ... })
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<form id="frmTest">
<input type="text" name="price_min">Min
<input type="text" name="price_max">Max
</form>
<button id="btn">Test Serialize</button>

Use jQuery to send the fields like this
$('your_form').submit(function() {
var min_price = $("#min_price").val();
var max_price = $("#max_price").val();
var string = "";
if(min_price.length > 0){
string += "min_price="+min_price
}
if(max_price.length > 0){
string += "&max_price="+max_price
}
window.location.href = 'index.php?'+string;
});
Hope it helps!

javascript form validation object

Please i just started learning javascript, In order to build my skill. I gave myself a javascript project to build an object validator.The first method i created is checkEmpty. This method check for empty field. But for reason unknow to me the method don't work.
This is the html form
<form name="myForm">
<input type="text" class="required email" name='fName'/>
<input type="text" class="required number" name="lName"/>
<input type="submit" value="submit" name="submit" id="submit"/>
</form>
This is the javascript that called the validator object
window.onload = function(){
var validate = new FormValidator('myForm');
var submit = document.getElementById('submit');
//this method won't work for internet explorer
submit.addEventListener('click',function(){return checkLogic();},false);
var checkLogic = function(){
validate.checkEmpty('fName');
};
}
This is the javascript object called Formvalidation
function FormValidator(myForm){
//check ur error in stack overflow;
this.myForm = document.myForm;
this.error = '';
if(typeof this.myForm === 'undefined'){
alert('u did not give the form name ');
return;
}
}
//this method will check wheather a field is empty or not
FormValidator.prototype.checkEmpty = function(oEmpty){
var oEmpty = this.myForm.oEmpty;
if(oEmpty.value === '' || oEmpty.value.length === 0){
this.error += "Please Enter a valid Error Message \n";
}
FormValidator.printError(this.error);
};
This method printout the error;
FormValidator.printError = function(oData){
alert(oData);
};

After formatting your code it got a lot easier to find out what went wrong. I assume you are trying to validate the input fields from your html code.
Your code is falling on its nose the first time in line 1 of the method checkEmpty():
FormValidator.prototype.checkEmpty = function(oEmpty){
var oEmpty = this.myForm.oEmpty;
if(oEmpty.value === '' || oEmpty.value.length === 0){
this.error += "Please Enter a valid Error Message \n";
}
FormValidator.printError(this.error);
};
In the first line you are hiding the methods argument oEmpty with the var oEmpty statement from line 1
There are several other issues like overusing methods and members. The following code is probably what you wanted:
1.) index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title></title>
</head>
<body>
<form name="myForm">
<input id="fName" name='fName' type="text"/>
<input id="lName" name="lName" type="text"/>
<input id="submit" name="submit" type="submit" value="submit"/>
</form>
<script src="main.js"></script>
</body>
</html>
2.) main.js
function InputFieldValidator(inputFieldName){
this.inputFieldName = inputFieldName;
this.inputField = document.getElementById(this.inputFieldName);
if(this.inputField === 'undefined'){
alert('No input field: ' + this.inputFieldName);
}
}
InputFieldValidator.prototype.validate = function(){
if(this.inputField.value === ''){
alert('Please enter valid text for input field: ' + this.inputFieldName);
}
};
window.onload = function(){
var fNameValidator = new InputFieldValidator('fName'),
lNameValidator = new InputFieldValidator('lName'),
submitButton = document.getElementById('submit');
submitButton.addEventListener('click', function (){
fNameValidator.validate();
lNameValidator.validate();
});
};
If you like you can wrap the input field validators from above easily in a form validator.

This is the right way to define functions this way:
var FormValidator = function(myForm){ /* function body */ };
FormValidator.prototype.checkEmpty = function(oEmpty){ /* function body */ };
Than, after instantiating the object, you can call FormValidator.checkEmpty(value) like you did.