If you already know your subject text doesn’t contain any invalid dates, you could use a trivial regex such as cannot repeat more than two times or fewer than two times.Solutions 3 through 6 restrict the month to numbers between 1 and 12, and the day to numbers between 1 and 31.The demo below , uses a function to check if value in the form field is empty or null.A simple six digit zipcode can be checked using regular expression which matches exactly six digits : /^d$/ Another way can be /^[0-9][0-9][0-9][0-9][0-9][0-9]$/ , for zipcode with dash in between it can be /^\d-? There may be some form fields whose values must be strictly alphabetic characters, eg: Name, Country, State.If you want to use async validation you need to use a runtime that supports Promises.You can tell to use any A compatible promise implemention like this: There are already many validation libraries out there today but most of them are very tightly coupled to a language or framework.In the below demo the regular expression looks for one or more uppercase or lowercase letters within the character class [A-Za-z], followed with an end of a line anchor $ Some undesired spaces and dashes from the user input can be removed by using the string object replace() method.
The project can be found on Git Hub where you can also find our issue tracker.You can’t tell a regular expression to “match a number between 1 and 31”, for instance. See Chapter 6 for more details on matching all kinds of numbers with regular expressions.Because of this, you have to choose how simple or how accurate you want your regular expression to be.It is very important to validate the data supplied by the user through a form before you process it. In the following examples, a Java Script function is used to check a valid date format against a regular expression.Among various kind of data validation, validation of date is one. Later we take each part of the string supplied by user (i.e.