Functions returning functions

function interviewQuestion(job){
  if(job === 'designer'){
    return function(name){
      console.log(name + ', can you please explain what UX design is?');
    }
  } else if (job === 'teacher'){
    return function(name){
      console.log('What subject do you teach, ' + name + '?');
    }
  } else {
    return function(name){
      console.log('What do you do?');
    }
  }
}

// A function is assigned to teacherQuestion since interviewQuestion returns a function
var teacherQuestion = interviewQuestion('teacher');
teacherQuestion('John'); // 'What subject do you teach, John?'
interviewQuestions('teacher')('John') // 'What subject do you teach, John?'

This is possible because functions are always first class functions. The functions are infact an object.

A language is said to have first class functions when the functions can be treated like any other variable. These first class functions can be assgined to a variable, passed to a function as an argument or be returned from a function.