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JavaScript : HTML Form validation - checking for password

Password validation

Sometimes a password validation in a form is essential. You can create a password in different ways, it's structure may be simple, reasonable or strong. Here we validate various type of password structure through JavaScript codes and regular expression.

  • Check a password between 7 to 16 characters which contain only characters, numeric digits and underscore and first character must be a letter.
  • Check a password between 6 to 20 characters which contain at least one numeric digit, one uppercase and one lowercase letter.
  • Check a password between 7 to 15 characters which contain at least one numeric digit and a special character.
  • Check a password between 8 to 15 characters which contain at least one lowercase letter, one uppercase letter, one numeric digit, and one special character.

Following code blocks contain actual codes for the said validations. We have kept the CSS code part common for all the validations.

CSS Code:

li {list-style-type: none;
font-size: 16pt;
}
.mail {
margin: auto;
padding-top: 10px;
padding-bottom: 10px;
width: 400px;
background : #D8F1F8;
border: 1px soild silver;
}
.mail h2 {
margin-left: 38px;
}
input {
font-size: 20pt;
}
input:focus, textarea:focus{
background-color: lightyellow;
}
input submit {
font-size: 12pt;
}
.rq {
color: #FF0000;
font-size: 10pt;
}

To check a password between 7 to 16 characters which contain only characters, numeric digits, underscore and first character must be a letter

To validate the said format we use the regular expression ^[A-Za-z]\w{7,15}$, where \w matches any word character (alphanumeric) including the underscore (equivalent to [A-Za-z0-9_]).  Next the match() method of string object is used to match the said regular expression against the input value. Here is the complete web document.

HTML Code:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
title>JavaScript form validation - Password Checking - 1</title>
<link rel='stylesheet' href='form-style.css' type='text/css' />
</head>
<body onload='document.form1.text1.focus()'>
<div class="mail">
<h2>Input Password and Submit [7 to 15 characters which contain only characters, numeric digits, underscore and first character must be a letter]</h2
<form name="form1" action="#">
<ul>
<li><input type='text' name='text1'/></li>
<li class="rq">*Enter numbers only.</li>
<li>&nbsp;</li>
<li class="submit"><input type="submit" name="submit" value="Submit" onclick="CheckPassword(document.form1.text1)"/></li>
<li>&nbsp;</li>
</ul>
</form>
</div>
<script src="check-password-1.js"></script>
</body>
</html>

JavaScript Code:

function CheckPassword(inputtxt) 
{ 
var passw=  /^[A-Za-z]\w{7,14}$/;
if(inputtxt.value.match(passw)) 
{ 
alert('Correct, try another...')
return true;
}
else
{ 
alert('Wrong...!')
return false;
}
}

View the example in the browser

To check a password between 6 to 20 characters which contain at least one numeric digit, one uppercase and one lowercase letter

To validate the said format we use the regular expression ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{4,8}$.  Next the match() method of string object is used to match the said regular expression against the input value. Here is the complete web document.

HTML Code:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>JavaScript form validation - Password Checking - 2</title>
<link rel='stylesheet' href='form-style.css' type='text/css' />
</head>
<body onload='document.form1.text1.focus()'>
<div class="mail">
<h2>Input Password and Submit [6 to 20 characters which contain at least one numeric digit, one uppercase and one lowercase letter]</h2>
<form name="form1" action="#">
<ul>
<li><input type='text' name='text1'/></li>
<li class="rq">*Enter numbers only.</li>
<li>&nbsp;</li>
<li class="submit"><input type="submit" name="submit" value="Submit" onclick="CheckPassword(document.form1.text1)"/></li>
<li>&nbsp;</li>
</ul>
</form>
</div>
<script src="check-password-2.js"></script>
</body>
</html>

JavaScript Code:

function CheckPassword(inputtxt) 
{ 
var passw = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{6,20}$/;
if(inputtxt.value.match(passw)) 
{ 
alert('Correct, try another...')
return true;
}
else
{ 
alert('Wrong...!')
return false;
}
}

View the example in the browser

To check a password between 7 to 15 characters which contain at least one numeric digit and a special character

To validate the said format we use the regular expression ^^(?=.*[0-9])(?=.*[[email protected]#$%^&*])[[email protected]#$%^&*]{7,15}$.  Next the match() method of string object is used to match the said regular expression against the input value. Here is the complete web document.

HTML Code:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>JavaScript form validation - Password Checking - 3</title>
<link rel='stylesheet' href='form-style.css' type='text/css' />
</head>
<body onload='document.form1.text1.focus()'>
<div class="mail">
<h2>Input Password and Submit [7 to 15 characters which contain at least one numeric digit and a special character]</h2>
<form name="form1" action="#">
<ul>
<li><input type='text' name='text1'/></li>
<li class="rq">*Enter numbers only.</li>
<li>&nbsp;</li>
<li><input type="submit" name="submit" value="Submit" onclick="allnumericplusminus(document.form1.text1)" /></li>
<li>&nbsp;</li>
</ul>
</form>
</div>
<script src="check-password-3.js"></script>
</body>
</html>

JavaScript Code

function CheckPassword(inputtxt) 
{ 
var paswd=  /^(?=.*[0-9])(?=.*[[email protected]#$%^&*])[[email protected]#$%^&*]{7,15}$/;
if(inputtxt.value.match(paswd)) 
{ 
alert('Correct, try another...')
return true;
}
else
{ 
alert('Wrong...!')
return false;
}
}  

View the example in the browser

To check a password between 8 to 15 characters which contain at least one lowercase letter, one uppercase letter, one numeric digit, and one special character

To validate the said format we use the regular expression ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s).{8,15}$.  Next the match() method of string object is used to match the said regular expression against the input value. Here is the complete web document.

HTML Code:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>JavaScript form validation - Password Checking - 4</title>
<link rel='stylesheet' href='form-style.css' type='text/css' />
</head>
<body onload='document.form1.text1.focus()'>
<div class="mail">
<h2>Input Password and Submit [8 to 15 characters which contain at least one lowercase letter, one uppercase letter, one numeric digit, and one special character]</h2>
<form name="form1" action="#">
<ul>
<li><input type='text' name='text1'/></li>
<li class="rq">*Enter numbers only.</li>
<li>&nbsp;</li>
<li><input type="submit" name="submit" value="Submit" onclick="allnumericplusminus(document.form1.text1)" /></li>
<li>&nbsp;</li>
</ul>
</form>
</div>
<script src="check-password-4.js"></script>
</body>
</html>

JavaScript Code:

function CheckPassword(inputtxt) 
{ 
var decimal=  /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s).{8,15}$/;
if(inputtxt.value.match(decimal)) 
{ 
alert('Correct, try another...')
return true;
}
else
{ 
alert('Wrong...!')
return false;
}
} 

View the example in the browser

javascript validation download codeDownload the Validation code from here

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JavaScript: Tips of the Day

JavaScript: function and arguments

const person = {
  name: 'Lydia Hallie',
  hobbies: ['coding'],
};

function addHobby(hobby, hobbies = person.hobbies) {
  hobbies.push(hobby);
  return hobbies;
}

addHobby('running', []);
addHobby('dancing');
addHobby('baking', person.hobbies);

console.log(person.hobbies);

The addHobby function receives two arguments, hobby and hobbies with the default value of the hobbies array on the person object.
First, we invoke the addHobby function, and pass "running" as the value for hobby and an empty array as the value for hobbies. Since we pass an empty array as the value for y, "running" gets added to this empty array.
Then, we invoke the addHobby function, and pass "dancing" as the value for hobby. We didn't pass a value for hobbies, so it gets the default value, the hobbies property on the person object. We push the hobby dancing to the person.hobbies array.
Last, we invoke the addHobby function, and pass "bdaking" as the value for hobby, and the person.hobbies array as the value for hobbies. We push the hobby baking to the person.hobbies array.
After pushing dancing and baking, the value of person.hobbies is ["coding", "dancing", "baking"]

Ref: https://bit.ly/2Hcpkm6