Trying my own thing

So I am taking this function and just putting it into my own editor, just for fun. Now how do i check if it works? I am using Atom.
Now everytime in try to


It tells me that fahrenheit is undefined ? So some clarification would be nice


function convertToF(celsius) {
  // Only change code below this line
  var fahrenheit = (celsius * (9/5)) + 32;

  // Only change code above this line
  if ( typeof fahrenheit !== 'undefined' ) {
  return fahrenheit;
  } else {
    return 'fahrenheit not defined';

// Change the inputs below to test your code


Where did you place the console.log?