Promise

Good commentary, but the Japanese translation is not very good.

The term "resolve is called asynchronously" is ambiguous.

I wrote, but now that I look at it, I couldn't find that expression.

As of 2021/2, it is written more clearly.

Note that promises are guaranteed to be asynchronous. Thus, an action on a promise that has already been "resolved" will be executed only after the stack has been cleared and a clock tick has elapsed. This effect is very similar to setTimeout(action,10)

---old

The term "resolve is called asynchronously" is ambiguous.

The first argument of Promise, (resolve, reject) => {...} Whether you call resolve synchronously or asynchronously in

code::

create promise start

promise body start

sync body start

sync body end

promise body end

create promise end

specify promise.then start

specify promise.then end

resolved ok

code:ts

const syncBody = (resolve: any, reject: any) => {

console.log("sync body start")

resolve("ok")

console.log("sync body end")

}

const asyncBody = (resolve: any, reject: any) => {

console.log("async body start")

setTimeout(() => {

console.log("timeout start")

resolve("ok")

console.log("timeout end")

}, 1000)

console.log("async body end")

}

console.log("create promise start")

let p = new Promise((resolve, reject) => {

console.log("promise body start")

syncBody(resolve, reject)

console.log("promise body end")

})

console.log("create promise end")

console.log("specify promise.then start")

p.then((x) => {

console.log("resolved", x)

})

console.log("specify promise.then end")

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