Validation.js

Syntactically awesome form validation in Javascript

Exmaples

$(input)
  .validates('is not blank')
  .validates('is an email address')
  .validates(function accountDoesNotAlreadyExist(value, complete){
    var validation = this;
    new Ajax.Request('username_available?username='+value,{
      onComplete: function(){
        complete();
      },
      onFailure: function(response) {
        validation.addError('is already taken');
      }
    });
  })
  .observe('validation:failure',function(event){
    $(input).addClassName('invalid');
  })
  .observe('validation:success',function(event){
    $(input).removeClassName('invalid');
  });
  
$(input).validate();