How to check if a textbox is empty using javascript

Question

I have a jsp page with some TextBoxes  Now I want to fill them with some information and click the submit button  But I need to check whether this TextBox is empty or not    How can I do this

User · Answer

lt pre gt  lt form name  myform   method  post  enctype  multipart form-data  gt       lt input type  text    id  name    name  name    gt    lt input type  submit   gt   lt  form gt  lt  pre gt    lt script language  JavaScript  type  text javascript  gt   var frmvalidator    new Validator  myform        frmvalidator EnableFocusOnError false        frmvalidator EnableMsgsTogether         frmvalidator addValidation  name   req   Plese Enter Name       lt  script gt    Note  before using the code above you have to add the gen validatorv31 js file

User · Answer

You can also check it using jQuery   It s quite easy    lt html gt       lt head gt           lt title gt jQuery  Check if Textbox is empty lt  title gt           lt script type  text javascript  src  js jquery 1 7 1 min js  gt  lt  script gt       lt  head gt       lt body gt           lt form name  form1  method  post  action    gt               lt label for  city  gt City  lt  label gt               lt input type  text  name  city  id  city  gt           lt  form gt           lt button id  check  gt Check lt  button gt           lt script type  text javascript  gt                   check   click function                       if      city   val                                 alert  Empty                          else                        alert  Contains          city   val                                                                  lt  script gt       lt  body gt   lt  html gt

User · Answer

The most simple way to do it without using javascript is using required      lt input type  text  ID  txtName   Width  165px  required     gt

User · Answer

Whatever method you choose is not freeing you from performing the same validation on at the back end

User · Answer

Using regexp   S will match non whitespace character anything but not a space  tab or new line  If your string has a single character which is not a space  tab or new line  then it s not empty  Therefore you just need to search for one character   S  JavaScript   function checkvalue          var mystring   document getElementById  myString   value       if  mystring match   S              alert   Empty value is not allowed            return false        else           alert  correct input            return true            HTML    lt form onsubmit  return checkvalue this   gt       lt input name  myString  type  text  value    id  myString  gt       lt input type  submit  value  check value    gt   lt  form gt

User · Answer

Using this JavaScript will help you a lot  Some explanations are given within the code    lt script type  text javascript  gt       lt  --          function Blank TextField Validator                        Check whether the value of the element             text name from the form named text form is null         if   text form text name value                         If it is display and alert box            alert  Please fill in the text field                  Place the cursor on the field for revision            text form text name focus                 return false to stop further processing            return  false                        If text name is not null continue processing         return  true                     -- gt   lt  script gt   lt form name  text form  method  get  action          onsubmit  return Blank TextField Validator    gt       lt input type  text  name  text name   gt       lt input type  submit  value  Submit  gt   lt  form gt

User · Answer

Canonical without using frameworks with added trim prototype for older browsers   lt html gt   lt head gt   lt script type  text javascript  gt     add trim to older IEs if   String trim      String prototype trim   function    return this replace    s   s   g            window onload function        onobtrusively adding the submit handler   document getElementById  form1   onsubmit function        needs an ID     var val   this textField1 value      this  is the form      if  val  null    val trim                 alert  Please enter something          this textField1 focus          return false     cancel submission           return true     allow submit        lt  script gt   lt  head gt   lt body gt   lt form id  form1  gt     lt input type  text  name  textField1  value      gt  lt br  gt     lt input type  submit    gt   lt  form gt   lt  body gt   lt  html gt    Here is the inline version  although not recommended I show it here in case you need to add validation without being able to refactor the code  function validate theForm       passing the form object   var val   theForm textField1 value    if  val  null    val trim               alert  Please enter something        theForm textField1 focus        return false     cancel submission       return true     allow submit     passing the form object in  this    lt form onsubmit  return validate this   gt     lt input type  text  name  textField1  value      gt  lt br  gt     lt input type  submit    gt   lt  form gt

[javascript] How to check if a textbox is empty using javascript

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