WellKnownSymbols (WN01)
1: // Asynchronous generator and iterator
2: async function* asyncNumberGenerator() {
3: let i = 0;
4: while (i < 5) {
5: await new Promise(res => setTimeout(res, 1000));
6: yield i++;
7: }
8: }
9: const asyncIterator = asyncNumberGenerator()[Symbol.asyncIterator](); //Symbol.asyncIterator must be used to iterate over result of async generator function
10:
11: (async ()=>{ // async IIFE
12:
13: console.log(await asyncIterator.next()) // { value: 0, done: false }
14:
15:
16: console.log(await asyncIterator.next()) // (after approximately 1 second) { value: 1, done: false }
17: })();
18:
19: // Also can be used with for await...of loop:
20: // (async () => {
21: // for await (const num of asyncNumberGenerator()) {
22: // console.log(num) // Log number when promise resolved in async generator
23: // }
24: // })();
Symbol.asyncIterator is used to obtain an asynchronous iterator from an asynchronous iterable, such as the one returned by an asynchronous generator function (async function*).
{ value: 0, done: false }
{ value: 1, done: false }
WellKnownSymbols context:
ES6 context:
- (2024) Notes about JS Closures. #ES6
- (2024) Notes about Javascript asynchronous programming. #ES6
- (2022) Modern Javascript books #ES6 #Doc
- (2021) JS learning start point #ES6
- (2021) Maximilian Schwarzmüller Javascript lecture #ES6
- (2021) Javascript interview question from Happy Rawat #ES6
- (2021) Javascript tests #ES6
- (2016) New unique features of Javascript (updated). #ES6
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