What is the basic usage of Promise?

The basic usage of Promise is to instantiate a Promise object to represent an asynchronous operation, and then handle the result of the asynchronous operation by calling the then method of the Promise object. Promise objects have three states: pending (in progress), fulfilled (successfully completed), and rejected (failed). When the asynchronous operation is successful, the Promise object’s state changes from pending to fulfilled, and the callback function in the then method is executed, passing the result of the asynchronous operation as a parameter. When the asynchronous operation fails, the Promise object’s state changes from pending to rejected, and the callback function in the catch method is executed, passing the error information of the asynchronous operation as a parameter. During the lifecycle of a Promise object, you can handle the result or error of the asynchronous operation by calling the then method or catch method, and you can execute a callback function that will be executed regardless of whether the asynchronous operation is successful or failed by calling the finally method.