Promise: chaining then()

chaining multiple promises can enhance readability

prerequisites for understanding

• reminder: the test passes when a fulfilled promise is returned
• a function given to then() fulfills (if it doesnt throw)

chain promises

• then() receives the result of the promise it was called on
• multiple then()s can be chained
• order of the then()s matters
• any of the things given to then() can resolve asynchronously (the real power of Promises)
• also asynchronously, the order still matters, promises wait, but don`t block

Links

spec The description of how a value given to `then()` becomes a resolved promise.
spec Looks like the description in the spec of what `then()` accepts and does with the given value.
article A long article introducing promises.