validation function error , 'length' of undefined :     var ClassSignUpValidation = function (){};
    
    ClassSignUpValidation.prototype.CheckName = function (_target)
    {
    return false;
    }
    
    ClassSignUpValidation.prototype.CheckPassword = function (_target)
    {
    return false;
    }
    
    //SUBMIT FORM VALIDATION
    ClassSignUpValidation.prototype.SubmitForm = function (event)
    {
      var sumbit_errorspan = $("#submit-errorResult");
      //array validation function
           var validators = [this.CheckName, this.CheckPassword];
           // bypass all function
           var valid = validators.reduce(function(valid, validator){
           return validator() && valid;
           }, true);
    
           if(valid){
           sumbit_errorspan.html('');
           }else{
           sumbit_errorspan.css('color', 'red');
           sumbit_errorspan.html('sumbit not requirements.');
           }
           return valid;
    }

i am making a validation function , submitForm function is to check other function return value true or false , but i have this error , i dont know why.

error

    Uncaught TypeError: Cannot read property 'length' of undefined