Java Script also lets you display helpful alerts to inform the user what information they have entered incorrectly and how they can fix it.
In this lesson we will be reviewing some basic form validation, showing you how to check for the following: This lesson is a little long, but knowing how to implement these form validation techniques is definitely worth the effort on your part.
to avoid any erroneous data to be inserted into the database. So let us learn some basics because I have written this article only focusing on beginners and students. Example I hope you now understand the basics of validation in Java Script, now let us create the one sample web application that demonstrates how to do validation.
The chunk of code elem.value will grab the string inside the input and by adding on length elem.value.length we can see how long the string is.If you do not return false then the message will be displayed to the user that all fields are required but the form will be post back and it gives you the second page directly. The condition that checks both text boxes for word are as in the following: In the preceding condition, first we ensure that the email id is not blank then we match the email id entered into the text box to the Regular Expression that is saved in the email Exp variable.Therefore the return false statement works similar to the Required Field validator of ASP. The entire function will be as follows: I hope you have understood it then the Solution Explorer will look like as in the following: In the preceding Solution Explorer, their are two ASP.Client side validation Validation done in the browser before sending the form data to the server using Java Script, j Query and VBScript is called client-side validation. Let us first create the web application with two web pages We are adding two web pages because our requirement is, in the first web page there is form data to be filled in by the user and only after validating the form data, the form will be redirected to the next page.Server Side Validation Validation done at the server level after sending the form data to the server but before entering the data into the database is called server-side validation. The first page source code Look at the preceding source code closely; see the id's of controls that play the important role in Java Script validation by reading the ASP. The design view of the preceding source code will look as in the following: I hope you have created the same form as above for demonstration purposes. Net controls values in Java Script are as: There are three main methods shown in the above image in the red square to read the ASP.