Promise.prototype.then()

The then() method of Promise instances takes up to two arguments: callback functions for the fulfilled and rejected cases of the Promise. It stores the callbacks within the promise it is called on and immediately returns another Promise object, allowing you to chain calls to other promise methods.

The then() method schedules callback functions for the eventual completion of a Promise — either fulfillment or rejection. It is the primitive method of promises: the thenable protocol expects all promise-like objects to expose a then() method, and the catch() and finally() methods both work by invoking the object’s then() method.

Syntax example: then(onFulfilled)