Say that we have a function called nameEqualsToItself how accept a person object as input that checks if the name property of the input object equal the same name property of the input object implemented like this:
const nameEqualsToItself = (person) => person.name === person.name
Can you find the input that makes nameEqualsToItself return false?
const personX = ???
console.log(nameEqualsToItself(personX)) // print `false`
It printed false.
const nameEqualsToItself = (person) => person.name === person.name
const personX = { name: NaN, };
console.log(nameEqualsToItself(personX))
const personX={};
personX.name=NaN;
OR simply
const personX={name:NaN};
a. If x or y are any of NaN, +∞𝔽, or -∞𝔽, return false. ref
It will return false only for NaN, because Number.POSITIVE_INFINITY === Number.POSITIVE_INFINITY returns true, and it is same for negative infinity as well.
Also if using a Getter or a Proxy returning different values each time :)
const personX = { get name() { return Math.random() } };
console.log(nameEqualsToItself(personX)); //This will return false as well
Using a Proxy.
"use strict";
const personNameEqualsItself = person => person.name === person.name;
const person = (() => {
let boolean = true;
return new Proxy({}, {get: (target, property) => property === "name" ? boolean = !boolean : undefined});
})();
console.log(personNameEqualsItself(person)); // false
console.log(personNameEqualsItself(person)); // false
console.log(personNameEqualsItself(person)); // false
const personX = new Proxy({}, { get (target, attr) { return /name/i.test(attr) ? Symbol('name') : target[attr]; });
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