Promise - MDN Web Docs Glossary: Definitions of Web-related terms 编辑

A Promise is an object that's returned by a function that has not yet completed its work. The promise literally represents a promise made by the function that it will eventually return a result through the promise object.

When the called function finishes its work asynchronously, a function on the promise object called a resolution (or fulfillment, or completion) handler is called to let the original caller know that the task is complete.

Learn more

To learn more, have a look at these links.

General knowledge

• Futures and promises

Technical reference

• Promise in the JavaScript Reference.
• Using promises