Async Await
Last updated
const foo = wrapToReturnPromise(function*() {
try {
var val = yield getMeAPromise()
console.log(val)
} catch (err) {
console.log('Error: ', err.message)
}
})function delay(milliseconds: number, count: number): Promise<number> {
return new Promise<number>(resolve => {
setTimeout(() => {
resolve(count)
}, milliseconds)
})
}
// async function always returns a Promise
async function dramaticWelcome(): Promise<void> {
console.log('Hello')
for (let i = 0; i < 5; i++) {
// await is converting Promise<number> into number
const count: number = await delay(500, i)
console.log(count)
}
console.log('World!')
}
dramaticWelcome()var __awaiter =
(this && this.__awaiter) ||
function(thisArg, _arguments, P, generator) {
return new (P || (P = Promise))(function(resolve, reject) {
function fulfilled(value) {
try {
step(generator.next(value))
} catch (e) {
reject(e)
}
}
function rejected(value) {
try {
step(generator['throw'](value))
} catch (e) {
reject(e)
}
}
function step(result) {
result.done
? resolve(result.value)
: new P(function(resolve) {
resolve(result.value)
}).then(fulfilled, rejected)
}
step(
(generator = generator.apply(thisArg, _arguments || [])).next()
)
})
}
function delay(milliseconds, count) {
return new Promise(resolve => {
setTimeout(() => {
resolve(count)
}, milliseconds)
})
}
// async function always returns a Promise
function dramaticWelcome() {
return __awaiter(this, void 0, void 0, function*() {
console.log('Hello')
for (let i = 0; i < 5; i++) {
// await is converting Promise<number> into number
const count = yield delay(500, i)
console.log(count)
}
console.log('World!')
})
}
dramaticWelcome()var __awaiter =
(this && this.__awaiter) ||
function(thisArg, _arguments, P, generator) {
return new (P || (P = Promise))(function(resolve, reject) {
function fulfilled(value) {
try {
step(generator.next(value))
} catch (e) {
reject(e)
}
}
function rejected(value) {
try {
step(generator['throw'](value))
} catch (e) {
reject(e)
}
}
function step(result) {
result.done
? resolve(result.value)
: new P(function(resolve) {
resolve(result.value)
}).then(fulfilled, rejected)
}
step(
(generator = generator.apply(thisArg, _arguments || [])).next()
)
})
}
var __generator =
(this && this.__generator) ||
function(thisArg, body) {
var _ = {
label: 0,
sent: function() {
if (t[0] & 1) throw t[1]
return t[1]
},
trys: [],
ops: []
},
f,
y,
t,
g
return (
(g = { next: verb(0), throw: verb(1), return: verb(2) }),
typeof Symbol === 'function' &&
(g[Symbol.iterator] = function() {
return this
}),
g
)
function verb(n) {
return function(v) {
return step([n, v])
}
}
function step(op) {
if (f) throw new TypeError('Generator is already executing.')
while (_)
try {
if (
((f = 1),
y &&
(t =
y[
op[0] & 2
? 'return'
: op[0]
? 'throw'
: 'next'
]) &&
!(t = t.call(y, op[1])).done)
)
return t
if (((y = 0), t)) op = [0, t.value]
switch (op[0]) {
case 0:
case 1:
t = op
break
case 4:
_.label++
return { value: op[1], done: false }
case 5:
_.label++
y = op[1]
op = [0]
continue
case 7:
op = _.ops.pop()
_.trys.pop()
continue
default:
if (
!((t = _.trys),
(t = t.length > 0 && t[t.length - 1])) &&
(op[0] === 6 || op[0] === 2)
) {
_ = 0
continue
}
if (
op[0] === 3 &&
(!t || (op[1] > t[0] && op[1] < t[3]))
) {
_.label = op[1]
break
}
if (op[0] === 6 && _.label < t[1]) {
_.label = t[1]
t = op
break
}
if (t && _.label < t[2]) {
_.label = t[2]
_.ops.push(op)
break
}
if (t[2]) _.ops.pop()
_.trys.pop()
continue
}
op = body.call(thisArg, _)
} catch (e) {
op = [6, e]
y = 0
} finally {
f = t = 0
}
if (op[0] & 5) throw op[1]
return { value: op[0] ? op[1] : void 0, done: true }
}
}
function delay(milliseconds, count) {
return new Promise(function(resolve) {
setTimeout(function() {
resolve(count)
}, milliseconds)
})
}
// async function always returns a Promise
function dramaticWelcome() {
return __awaiter(this, void 0, void 0, function() {
var i, count
return __generator(this, function(_a) {
switch (_a.label) {
case 0:
console.log('Hello')
i = 0
_a.label = 1
case 1:
if (!(i < 5)) return [3 /*break*/, 4]
return [4 /*yield*/, delay(500, i)]
case 2:
count = _a.sent()
console.log(count)
_a.label = 3
case 3:
i++
return [3 /*break*/, 1]
case 4:
console.log('World!')
return [2 /*return*/]
}
})
})
}
dramaticWelcome()