async 完全理解 - 全ての async は Promise に通ず / Guide to async, await

Transcript

4. Promise Deferred Objects async await Promise async await
6. Promise<T> ( ) ( ) resolve(T) Promise reject(any) Promise then(f, f) , ,
7. Promise<T> ( ) ( ) resolve(T) Promise reject(any) Promise then(f, f) , ,
8. async return throw await const value = await ; console.debug(value); .then((value) => { console.debug(value); });
12. const promise = new Promise(); // ... ... promise.resolve( ); /* */ promise.reject( ); new Promise((resolve, reject) => { // ... ... resolve( ); /* */ reject( ); });
13. // Promise let resolve, reject; new Promise((_resolve, _reject) => { // resolve, reject resolve = _resolve; reject = _reject; }); resolve( ); /* */ reject( ); // ↑ ...
14. function () { // Promise ... const promise = new Promise(); // ... ( promise.resolve ) ... return promise; } const promise = (); promise.resolve(null); // resolve
15. function () { // Promise return new Promise((resolve, reject) => { // ... ( resolve ) ... }); } const promise = (); // ↑ resolve
16. function (props) { // const hoge = props.something.foobar(); // Promise ... const promise = new Promise(); // ... ( promise.resolve ) ... return promise; } resolve( ) reject( )
18. function () { /* ※1 */ return new Promise((resolve, reject) => { // reject( ) }); } const promise = (); // ↑ Promise reject ※1
19. promise.then .then((result) => { return (); // Promise }).then((result) => { // result === });
20. Promise.all(Promise<T>[]): Promise<T[]> Promise.race(Promise<T>[]): Promise<T> promise.catch(f)
21. function myFunction() { A().then((resultA) => { if (resultA === "hoge") { B().then((resultB) => { if (resultB === "huga") C(); }); } else { D().then((resultC) => { if (resultC === "piyo") E(); }); } }); }
24. async return throw await const value = await ; console.debug(value); .then((value) => { console.debug(value); });
25. await // async function myFunction() { if (await A() === "hoge") { if (await B() === "huga") C(); } else { if (await D() === "piyo") E(); } } await then
27. Promise Promise.all Promise.race await Promise.all( 1(), 2(), ...) Promise
28. async await async Promise Promise await await
31. async await function hoge() { const async = 1; const await = 2; console.log(async, await); // it works } async await async function() { ... } async
32. await async function myFunction() { await 1(); // 1().then(...) 1(); 2(); // await 2(); await 3(); // 3().then(...) } 2 no-floating-promises
33. await Promise.resolve(Promise.resolve(123)); // Promise.resolve(123) 123 // Promise.resolve Promise
34. fulfill reject resolve Promise.reject(e) Promise.resolve(value) fulfill resolve reject
35. new Promise Promise. Promise
36. Promise Promise Promise = undefined; // Promise.resolve(1234); // await (async() => 123)(); // async await Promise Promise ZoneAwarePromise Promise Zone async await Promise.
37. await then await 14.6.13 Runtime Semantics: Evaluation 25.5.5.3 AsyncFunctionAwait ( value ) 25.4.5.3.1 PerformPromiseThen
38. await