86. Promise.resolve and Promise.reject Polyfill

Implement Promise.resolve and Promise.reject static methods that create resolved and rejected promises.

These static methods are essential utilities for working with Promises:

• Promise.resolve(value): Creates a resolved promise with the given value
• Promise.reject(reason): Creates a rejected promise with the given reason

1. Promise.resolve

• Accept any value (promise, thenable, or plain value)
• Return a promise that resolves with the value
• If value is a promise, return it as-is
• If value is a thenable, follow the thenable
• If value is plain, wrap it in a resolved promise

2. Promise.reject

• Accept any rejection reason
• Return a promise that rejects with the reason
• Always reject (even if reason is a promise)

3. Edge Cases

• Handle null/undefined values
• Handle already settled promises
• Handle thenables (objects with then method)

Examples

// Promise.resolve
Promise.resolve(42).then(console.log); // 42
Promise.resolve(Promise.resolve(1)).then(console.log); // 1

// Promise.reject
Promise.reject('error').catch(console.log); // 'error'
Promise.reject(new Error('fail')).catch(err => err.message); // 'fail'

// Thenable handling
const thenable = { then: (resolve) => resolve('thenable') };
Promise.resolve(thenable).then(console.log); // 'thenable'