How Should I Think Of Property Definitions In Object Literals?

let o = { x: 1, foo() { setTimeout(()=> console.log(this.x), 100); } } o.foo(); This prints out 1 after 100ms. Is this because it is equivalent to the foll

Solution 1:

Is this because it is equivalent to the following, meaning that the lexical this binding of arrow functions works?

No, it's much simpler than that. It's equivalent to

var o = {
  x: 1,
  foo: function() {
    setTimeout(()=>console.log(this.x),
    100);
  }
};
o.foo();

and with the arrow function converted:

var o = {
  x: 1,
  foo: function() {
    var self = this;
    setTimeout(function() {
      console.log(self.x)
    }, 100);
  }
};
o.foo();

Since you are calling o.foo(), this inside foo refers to o. Because an arrow function's this is subject to lexical scope, it access foo's this.