this-js

this.js

var obj = {
   a: 5,
   b: 10,
   add: function() {
      return this.a + this.b;
   },
};
console.log('1: ', obj.add());

var another = obj.add;
console.log('2: ', another());

var anotherBound = obj.add.bind(obj);
console.log('3: ', anotherBound());

var obj2 = {
    c: 5,
    d: 10,
    add: {
      e: 15,
      fun: function() {
          console.log('4: inner: ', this.c, this.d, this.e);
      }
    },
    subtract: function() {
      this.e = 15;
      console.log('5: outer: ', this.c, this.d, this.e);
      return function() {
          console.log('5: inner: ', this.c, this.d, this.e);
      };
    },
};

console.log('4: ', obj2.add.fun());
console.log('5: ', obj2.subtract()());