ASP.Net: Text Box Validation Part I

Introduction

In this article, I explain some more validations of Text box control in ASP.Net.

Requirement

Add the following line in the head section to create a function for validation.

  1. <script language="javascript" type="text/javascript">

Then create a function:

  1. function validate()
  2. {
  3. . //function body
  4. .
  5. .
  6. return true;
  7. }

Solution

  1. Text box cannot be blank :

    This kind of validation does not allow blank text box controls in ASP.Net. Add the following function body:

    1. if (document.getElementById("<%=txtName.ClientID%>").value=="")
    2. {
    3. alert("Name Feild can not be blank");
    4. document.getElementById("<%=txtName.ClientID%>").focus();
    5. returnfalse;
    6. }

    Where txtName is the Id of a Text Box control.

  2. Email id Validation

    This kind of validation accepts only email id syntax in a text box control in ASP.Net. Add the following function body:

    1. if(document.getElementById("<%=txtEmail.ClientID %>").value=="")
    2. {
    3. alert("Email id can not be blank");
    4. document.getElementById("<%=txtEmail.ClientID %>").focus();
    5. returnfalse;
    6. }
    7. var emailPat = /^(\".*\"|[A-Za-z]\w*)@(\[\d{1,3}(\.\d{1,3}){3}]|[A-Za-z]\w*(\.[A-Za-z]\w*)+)$/;
    8. var emailid=document.getElementById("<%=txtEmail.ClientID %>").value;
    9. var matchArray = emailid.match(emailPat);
    10. if (matchArray == null)
    11. {
    12. alert("Your email address seems incorrect. Please try again.");
    13. document.getElementById("<%=txtEmail.ClientID %>").focus();
    14. returnfalse;
    15. }

    Where txtEmail is the Id of a Text Box.

  3. Web URL

    This kind of validation only accepts a web URL in a Text box control. Add the following function body:

    1. if(document.getElementById("<%=txtWebURL.ClientID %>").value=="")
    2. {
    3. alert("Web URL can not be blank");
    4. document.getElementById("<%=txtWebURL.ClientID %>").value="http://"
    5. document.getElementById("<%=txtWebURL.ClientID %>").focus();
    6. returnfalse;
    7. }
    8. var Url="^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$"
    9. var tempURL=document.getElementById("<%=txtWebURL.ClientID%>").value;
    10. var matchURL=tempURL.match(Url);
    11. if(matchURL==null)
    12. {
    13. alert("Web URL does not look valid");
    14. document.getElementById("<%=txtWebURL.ClientID %>").focus();
    15. returnfalse;
    16. }

    Where txtWebURL is the Id of a Text Box.

  4. ZIP Format

    This kind of validation only accepts a ZIP format of data in the Text Box control in ASP.Net. Add the following function body:

    1. if (document.getElementById("<%=txtZIP.ClientID%>").value=="")
    2. {
    3. alert("Zip Code is not valid");
    4. document.getElementById("<%=txtZIP.ClientID%>").focus();
    5. returnfalse;
    6. }
    7. var digits="0123456789";
    8. var temp;
    9. for (var i=0;i<document.getElementById("<%=txtZIP.ClientID %>").value.length;i++)
    10. {
    11. temp=document.getElementById("<%=txtZIP.ClientID%>").value.substring(i,i+1);
    12. if (digits.indexOf(temp)==-1)
    13. {
    14. alert("Please enter correct zip code");
    15. document.getElementById("<%=txtZIP.ClientID%>").focus();
    16. returnfalse;
    17. }
    18. }

    Where txtZIP is the Id of a text box.

    When you done with all call the function validate on the Button on which you want output as in the following :

    1. <asp:Button ID="btnSubmit" OnClientClick=" return validate()" runat="server" Text="Submit" />

Now save the entire work and view the page in a browser. It will work perfectly.