Using promises
The traditional way to handle an asynchronous operation is to use callback functions for the success or failure of the operation. One of these callback functions is called (success or failure), depending on the result of the call. The following example shows the idea of using a callback function:
function doAsyncCall(success, failure) {
// Do some API call
if (SUCCEED)
success(resp);
else
failure(err);
}
success(response) {
// Do something with response
}
failure(error) {
// Handle error
}
doAsyncCall(success, failure);
A promise is an object that represents the result of an asynchronous operation. The use of promises simplifies the code when you're executing asynchronous calls. Promises are non-blocking.
A promise can be in one of three states:
- Pending: Initial state
- Fulfilled: Successful operation
- Rejected...
