JS constructor, factory, class

js-object-creation.js

//***  Object creation

// 1) class syntax , usage: p = new Person('Rex')
class Person {

  constructor(name) {
    this.name = name
  }

  sayHello() {
    console.log(`Hi, I'm ${this.name}`)
  }

}


// 2) constructor function, usage: p = new Person('Rex')
function Person(name) {
  this.name = name
}

Person.prototype.hello = function () {
  console.log(`Hi, I'm ${this.name}`)
}

//method
const helloMethod = function () {
  console.log(`Hi, I'm ${this.name}`)
}

// 3) factory function, usage: p = createPerson('Rex')
function createPerson(name) {
  const ret = {
    name,

  }
  ret.hello = helloMethod
  return ret
}

const p = createPerson('rex')
p.name = 'XXXX'
p.hello()


//*** functions as arguments and return values for/of other functions

function wrapWithLogging(fn) {
  return () => {
      console.log(`calling...`)
      const ret = fn()
      console.log(`returned: ${ret}`)
      return ret
  }
}


const f1 = wrapWithLogging(wrapWithLogging( ()=> {
  return 'F one'
}))


f1()