引数を指定しているのに、関数が未定義を返すのはなぜですか

私を信じてください、前の答えは正しい方法でしたが、あなたがあなた自身のフローを試したいなら、ここに解決策があります、それは遅くなります、多くの不要な変数、たくさんのコーディングなどあなたはからのコードで遊ぶことができますjsbin

// declare global
// getting form by id (jquery), 
// it is always good practise to define your element in global scope
// we used $somename for jquery specific names
// remember $('somekelement') is a heavy function of jQuery 
// which did lots of calculation behind the scene
// this is why i am declaring it only once 
// it will help me to not used $('#myform') every time, need to access form 
var $myform = $('#myform');

// for your logic i wanted two extra boolean to check if my password and confirm_password i created or not.
var isPassword = false; // by default not created
var isConfirmPassword = false; // false means not created true means created.

// this is your function that create a input and some logic as per your requirements
function getPassword() {

  if(!isPassword) {
    let pwd = $('<input/>', {
          type:'text',
          name:'password',
         'placeholder':'Password'
       }).on('blur', function() {

          if(false) {
            //more unrelated code
          } else {
            $(this).css({
                'color': 'gray',
                'border': '1px solid green'
            });
            let cValue = $(this).val();

            console.log("Your cValue: "+ cValue); // here you are getting your values right.

            let x = getPasswordConfirm(cValue);   // here you are calling another function that generate another input
          }
        });
      return pwd;
      isPassword = true;
    }
};


// if this function is generating new input, then it must not be called inside of getPassword function, because blur event may occur multiple times and each blur will create new confirm_password fields
// here i think logically not possible, 
// only possible way here is to distribute your coding into two section
// 1st section will build all your dynamic input fields
// 2nd section will validate your inputs.
function getPasswordConfirm(cValue) {
  window.cValue = cValue; // i saved cValue here in global namespace so next time.
    console.log('argument cValue: '+cValue); // wola, you got the value here.

  // but sadly, you didn't have c_pwd yet, so you couldn't be able to fire blur event here.
  // Your blur event will be created but if will fire on out of focus, but next time cValue will not be passed
  // because it will happened only one time or you will have multiple inputs each trying to catch a event before born to the world
  if(!isConfirmPassword) {
    let c_pwd = ($('<input/>', {  // changed name to c_pwd
       type:'text',
       name:'confirm_password',
      'placeholder':'Confirm Password'
    })).on('blur', function() {
      console.log('What was cValue: '+ window.cValue);
        if(false) {
            //unrelated code
        } else {
            if ($(this).val() !== cValue) {
                    console.log('====rock you got cValue here : '+cValue); // getting this value here as well. but problem is that you are getting multiple inputs
                //this is where it goes wrong, cValue is undefined???
            } else {
                $(this).css({
                    'color': 'gray',
                    'border': '1px solid green'
                });
                console.log(cValue);
            }
        }
    }.bind(this)); // you can also bind your subscope to their parent scope by bind funciton, in new ES6 we create arrow function (arg1, arg2) => {console.log(arg1,arg2);}

    isConfirmPassword = true;

    //return c_pwd; // comment this line and uncomment next line see result by yourself. 
    $myform.append(c_pwd); // i am appending confirm_password input on blur on password result will create multiple confirm boxes   
  }
};


$myform.append(getPassword());

// suppose your two function build your form then code for appending will be like that
//$myform.append(getPassword()).append(getPasswordConfirm());