Learning about Optional Chaining

optchains.js

// ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining
// fiddle: https://jsfiddle.net/tulsiprasad/hou3jrf8/120

const user = {
  firstName: "Jade",
  lastName: "Wilson",
  address: {
  	home: {
    	street: "2502 Bennie Dr",
      state: "Pearson, Georgia(GA)",
      tel: "(912) 534-5614"
    },
    work: {
    	street: "774 Poplar Grove Rd",
      state: "Boone, North Carolina(NC)",
      tel: "(828) 386-1840"
    }
  },
  fullName: function() {
    return `${this.firstName} ${this.lastName}`
  },
  pets: ["Whoosh", "Fluffy", "Bolt"]
}

console.log(user.address.school.state) // TypeError: Cannot read property 'state' of undefined
console.log(user.completeName()) // TypeError: user.completeName is not a function
console.log(user.pets[12].toLowerCase()) // TypeError: Cannot read property 'toLowerCase' of undefined
console.log(user.address["school"]["street"]) // TypeError: Cannot read property 'street' of undefined

console.log(user.address.school?.state) // undefined
console.log(user.completeName?.()) // undefined
console.log(user.pets[12]?.toLowerCase()) // undefined
console.log(user.address["school"]?.["street"]) // undefined
console.log(user.address?.home?.state?.lane) // undefined
console.log(user.pets?.[12]?.name) // undefined
            
console.log(user.fullName?.()) // Jade Wilson
console.log(user.address?.home?.state) // Pearson, Georgia(GA)
console.log(user.address?.["work"]?.["state"]) // Boone, North Carolina(NC)
console.log(user.pets?.[1]) // Fluffy