Javascript This and Double Arrow Functions

util = {  message: 'hello',  test1() {    // return hello    return this.message  },  test2: function() {    return this.message  },  test3: () => {    // this = window    return this.message  }}console.log(util.test1()) // helloconsole.log(util.test2()) // helloconsole.log(util.test3()) // undefined - this = global window

util = {  message: 'hello',  test4() {    const test = () => {      return this.message    }    return test()  },  test5() {    const test = function() {      return self.message    }    return test()  },  test6() {    const self = this    const test = function() {      return self.message    }    return test()  }   }console.log(util.test4()) // helloconsole.log(util.test5()) // undefined - this = global windowconsole.log(util.test6()) // hello