Check Name Field For Free

String regularExpression= "^[A-Za-z][A-Za-z0-9_]{7,29}$"; A valid username should start with an alphabet so, [A-Za-z]. All other characters can be alphabets, numbers or an underscore so, [A-Za-z0-9_]. Since length constraint was given as 8-30 and we had already fixed the first character, so we give {7,29}.

How to set up validation with HTML5 functionality Making fields required using required. Constraining the length of data: minlength , maxlength : for text data. ... Restricting the type of data using type : <input type="email" name="multiple> Specifying data patterns using pattern :

To get a string contains only letters (both uppercase or lowercase) we use a regular expression (/^[A-Za-z]+$/) which allows only letters. Next the match() method of string object is used to match the said regular expression against the input value.

The simplest HTML validation feature is the required attribute. To make an input mandatory, add this attribute to the element. When this attribute is set, the element matches the :required UI pseudo-class and the form won't submit, displaying an error message on submission when the input is empty.

To validate the form using HTML, we will use HTML <input> required attribute. The <input> required attribute is a Boolean attribute that is used to specify the input element must be filled out before submitting the Form.

Using JavaScript, the full name validation can be easily implemented in the form to check whether the user provides their first name and last name properly. The REGEX (Regular Expression) is the easiest way to validate the Full Name (first name + last name) format in JavaScript.

JavaScript Form Validation Example <script> function validateform(){ var name=document.myform.name.value; var password=document.myform.password.value; if (name==null || name==""){ alert("Name can't be blank"); return false; }else if(password.length<6){