Higher Order Function in Js

Feb 15, 2021 #fp #js

A bare mininum demonstration.

const studentGrades = [ 
  {name: 'Joe', grade: 88},
  {name: 'Jen', grade: 94},
  {name: 'Steph', grade: 77},
  {name: 'Allen', grade: 60},
  {name: 'Gina', grade: 54}, 
];

const messages = {
  a: 'Excellent Job',
  b: 'Nice Job',
  c: 'Well done',
  d: 'What happened',
  f: 'Not good',
};

function letterGrade(points){
  if (points >= 90){
    return 'a';
  } else if (points >= 80){
    return 'b'; 
  } else if (points >= 70){
    return 'c'; 
  } else if (points >= 60){
    return 'd'; 
  } else {
    return 'f'; 
  }
}

function feedBack(student){
    const grade = letterGrade(student.grade);
    const message = messages[grade];
    return `${message} ${student.name}, you got an ${grade}`;
}

const gradeFeedback = studentGrades.map(x => feedBack(x));
console.log(gradeFeedback);

// the rest above remains the same

function feedBack(feedbackRules){
    return function(student) {
        const grade = letterGrade(student.grade);
        const message = feedbackRules[grade];
        return `${message} ${student.name}, you got an ${grade}`;
    }
}

const gradeFeedback = studentGrades.map(feedBack(messages));
console.log(gradeFeedback);