Async Programming

Promise All

Promise.all waits for several promises and returns their values together.

Promise.all `Promise.all` receives an array of promises and resolves when every promise resolves.

Promise All

secondName
all.ts
Replay: real traced execution (multi-file project)
async function loadLabel(name: string): Promise<string> {
    return Promise.resolve(name.toUpperCase());
}

const secondName: string = "script";

async function main(): Promise<void> {
    const labels: string[] = await Promise.all([
        loadLabel("type"),
        loadLabel(secondName),
    ]);
    console.log(labels.join(","));
}

main();

async function loadLabel(name: string): Promise<string> {
    return Promise.resolve(name.toUpperCase());
}

const secondName: string = "types";

async function main(): Promise<void> {
    const labels: string[] = await Promise.all([
        loadLabel("type"),
        loadLabel(secondName),
    ]);
    console.log(labels.join(","));
}

main();

async function loadLabel(name: string): Promise<string> {
    return Promise.resolve(name.toUpperCase());
}

const secondName: string = "async";

async function main(): Promise<void> {
    const labels: string[] = await Promise.all([
        loadLabel("type"),
        loadLabel(secondName),
    ]);
    console.log(labels.join(","));
}

main();

  1. secondName ← script

    2    return Promise.resolve(name.toUpperCase());3}45const secondName→ script: string = "script";  //@secondName="types", "async"67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondName),11    ]);12    console.log(labels.join(","));13}1415main();

  2. //@secondName="types", "async" async function main(): Promise<void>

    5const secondName: string = "script";  //@secondName="types", "async"67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNamescript),11    ]);12    console.log(labels.join(","));

  3. async function loadLabel(name: string): Promise<string>

    pass 1 of 2
    1async function loadLabel(nametype: string): Promise<string> {2    return Promise.resolve(nametype.toUpperCase());3}

  4. async function loadLabel(name: string): Promise<string>

    pass 2 of 2
    1async function loadLabel(namescript: string): Promise<string> {2    return Promise.resolve(namescript.toUpperCase());3}

  5. labels ← TYPE,SCRIPT

    7async function main(): Promise<void> {8    const labels→ TYPE,SCRIPT: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNamescript),11    ]);12    console.log(labelsTYPE,SCRIPT.join(","));13}1415main();
    outputTYPE,SCRIPT

  1. secondName ← types

    2    return Promise.resolve(name.toUpperCase());3}45const secondName→ types: string = "types";67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondName),11    ]);12    console.log(labels.join(","));13}1415main();

  2. async function main(): Promise<void>

    5const secondName: string = "types";67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNametypes),11    ]);12    console.log(labels.join(","));

  3. async function loadLabel(name: string): Promise<string>

    pass 1 of 2
    1async function loadLabel(nametype: string): Promise<string> {2    return Promise.resolve(nametype.toUpperCase());3}

  4. async function loadLabel(name: string): Promise<string>

    pass 2 of 2
    1async function loadLabel(nametypes: string): Promise<string> {2    return Promise.resolve(nametypes.toUpperCase());3}

  5. labels ← TYPE,TYPES

    7async function main(): Promise<void> {8    const labels→ TYPE,TYPES: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNametypes),11    ]);12    console.log(labelsTYPE,TYPES.join(","));13}1415main();
    outputTYPE,TYPES

  1. secondName ← async

    2    return Promise.resolve(name.toUpperCase());3}45const secondName→ async: string = "async";67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondName),11    ]);12    console.log(labels.join(","));13}1415main();

  2. async function main(): Promise<void>

    5const secondName: string = "async";67async function main(): Promise<void> {8    const labels: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNameasync),11    ]);12    console.log(labels.join(","));

  3. async function loadLabel(name: string): Promise<string>

    pass 1 of 2
    1async function loadLabel(nametype: string): Promise<string> {2    return Promise.resolve(nametype.toUpperCase());3}

  4. async function loadLabel(name: string): Promise<string>

    pass 2 of 2
    1async function loadLabel(nameasync: string): Promise<string> {2    return Promise.resolve(nameasync.toUpperCase());3}

  5. labels ← TYPE,ASYNC

    7async function main(): Promise<void> {8    const labels→ TYPE,ASYNC: string[] = await Promise.all([9        loadLabel("type"),10        loadLabel(secondNameasync),11    ]);12    console.log(labelsTYPE,ASYNC.join(","));13}1415main();
    outputTYPE,ASYNC