1.3.11 – Change the label

I am practicing cloning nodes and making some changes. I was able to change the place holder text for the 2nd field but am having trouble changing the actual label (from “Field” to “Field 2” or whatever). Here is the code with my additions. I am getting a “Uncaught TypeError: Cannot read property ‘innerText’ of undefined(…)” error when I try to change the label text. What am I missing here?

 var fieldsList = document.querySelector( '.fields' ),
     firstField = fieldsList.children[0],
     firstFieldInput = firstField.querySelector( 'input' ),
     firstFieldIdStr = firstFieldInput.getAttribute( 'id' ),
     firstFieldPlaceholder = firstFieldInput.getAttribute( 'placeholder' ),
     secondField = firstField.cloneNode( true ),
     secondFieldInput = secondField.querySelector( 'input' ),
     secondFieldLabel = secondField.querySelector( 'label' ),
     secondFieldIdStr = updateIdStr( firstFieldIdStr ),
     secondFieldPlaceholder = secondField.querySelector( 'input' );
     secondFieldText = secondFieldLabel.innerText;

console.log( secondFieldText );

 secondFieldLabel.setAttribute( 'label', secondFieldIdStr );
 secondFieldText.innerText( secondFieldIdStr );
 secondFieldInput.setAttribute( 'id', secondFieldIdStr );
 secondFieldInput.setAttribute( 'name', secondFieldIdStr );
 secondFieldLabel.setAttribute( 'for', secondFieldIdStr );
 secondFieldPlaceholder.setAttribute( 'placeholder', 'Field 2 Text' );

 fieldsList.appendChild( secondField );

 function updateIdStr( value ) {

   var strArray = value.split( '-' ),
       id = strArray[ strArray.length - 1 ],
       newId = parseInt( id ) + 1;

   strArray[ strArray.length - 1 ] = newId;
   return strArray.toString().replace( ',' , '-' );

 }