Arrow function 'this' works not as expected

Question

Code here:

const a = {
  target: 'a',
  getTarget: () => {
    setTimeout(() => {
      console.log(this.target)
    }, 1000)
  },
}
window.target = 'window';
a.getTarget();

I thought it will print 'a', but it turns out to be 'window'.

Answer 1

This is because of the first arrow function you use:

const a = {
  target: 'a',
  getTarget(){
    setTimeout(() => {
      console.log(this.target)
    }, 1000)
  },
}
window.target = 'window';
a.getTarget();// a