Can we return document.createElement("element")?

I have to create an input box multiple times, so I call a function like this multiple times:

function __createInputBox(id) {
    var input = document.createElement("input");

    input.setAttribute('id', id);
    input.setAttribute('type', 'number');
    input.setAttribute('name', id);
    input.setAttribute('value', '0');
    input.setAttribute('min', '0');

    return input;
}

In my main function, I append it as such:

var box = __createInputBox(id);
element.appendChild(box);

I keep getting this error:

__createInputBox is not defined

So are we allowed to return the value from document.createElement("element")? If its bad to do so, what is the better way to add multiple elements to the page?

This how I declare the function:

function InputSpace(){
this.inputSpace = document.getElementById("inputspace");
this.num = 1;

    function __createInputBox(id) {
       // function  declared here
    }

This is the code where I call it:

InputSpace.prototype = {
constructor: InputSpace,
drawInputSpace : function () {
  var i = 0,
      max;
  var table = document.createElement("TABLE");
  var table_body = document.createElement("TBODY");
  for(max = num; i<num; i++){
        var element = document.createElement("TR");
        var box = __createInputBox(id);
        element.appendChild(box);
        table_body.appendChild(element);
  }
  table.appendChild(table_body);
  this.inputSpace.appendChild(table);
}

Copyright Notice：Content Author:「sharon」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/34338706/can-we-return-document-createelementelement