ES6 Arrow Functions - this

es6-arrow-functions-this.js

// ##########  ES6 Arrow Functions  ################
// ########## this no longer bound ################
// Note: when running the code on an fat-arrow-enabled runtime

// 1.
let aFunc = ()=>{
  return this
}

// 2.
let o = {}
o.func = aFunc;

// 3.
let Person = ()=>{
  this.func = aFunc;
}

// 4.
class Animal {
  constructor(){
    this.func = aFunc;
  }
}

// Invocations:

// 1.
console.log('this as a function: ', aFunc())
// => this as a function:  Window

// 2.
console.log('this as a method: ', o.func())
// => this as a method:  Window

// 3.
try {
    let person = new Person();
} catch (e) {
    console.log(e);
}
// => TypeError: Cannot set property 'func' of Window

// 4.
let animal = new Animal();
console.log('this as class method: ', animal.func())
// => this as class method:  Window

// 5. Apply and call do not work either
console.log('this a a given via apply: ', aFunc.apply({banana: 'Love Banana'}))
// => this a a given via apply:  Window

console.log('this a a given via call: ',aFunc.call({banana: 'Love Banana'}))
// => this a a given via call:  Window