Alchemy University 学习教程，Networks（第三周）

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January 4th, 2023

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第三周实际操作的只有一节内容：

Asynchronous JavaScript

Callback Functions

1: Run Callback

查看要求：

输入：

/**
 * Runs a callback function immediately
 * @param {function} callbackFunction
 */
function runCallback(callbackFunction) {
    callbackFunction();
}

module.exports = runCallback;

点击运行。

2: Run Callback Async

查看要求：

输入：

/**
 * Runs a callback function immediately
 * @param {function} callbackFunction
 */
function runCallback(callbackFunction) {
    setTimeout(callbackFunction, 1000);
}

module.exports = runCallback;

点击运行。

3: Dialog Callback

查看要求：

输入：

class Dialog {
    onClose(callbackFunction) {
        this.c = callbackFunction;
    }

    close() {
        this.c();
    }
}

module.exports = Dialog;

点击运行。

4: Dialog Callbacks

查看要求：

class Dialog {
    onClose(callbackFunction) {
        this.carr = this.carr || [];
        this.carr.push(callbackFunction);
    }

    close() {
        for (let i = 0; i < this.carr.length; i++) {
            this.carr[i]();
        }
    }
}

module.exports = Dialog;

点击运行。

5: For Each Callback

查看要求：

输入：

function forEach(arr, callback) {
    for (let i = 0; i < arr.length; i++) {
        callback(arr[i], i);
    }
}

module.exports = forEach;

点击运行。

6: Map Callback

查看要求：

输入：

function map(arr, callback) {
    let a = [];
    for (let i = 0; i < arr.length; i++) {
        a.push(callback(arr[i]));
    }

    return a;
}

module.exports = map;

点击运行。

Introduction to Promises

1: Request Order

查看要求：

输入：

const { makeFood } = require('./Kitchen');

class Order {
    constructor() {
        this.isReady = false;
    }
    request(food) {
        const promise = makeFood(food);
        promise.then( (food) => {
            this.isReady = true;
        });
    }
}

module.exports = Order;

点击运行。

2: Catch Error

查看要求：

输入：

const { makeFood } = require('./Kitchen');

class Order {
    constructor() {
        this.isReady = false;
    }
    request(food) {
        const promise = makeFood(food);
        promise.then( (food) => {
            this.isReady = true;
        });
        promise.catch((err) => {
            this.error = err;
        });
    }
}

module.exports = Order;

点击运行。

3: Create Promise

查看要求：

function timer() {

    const promise = new Promise(function(resolve, reject) {
        resolve('resolve');
    });

    return promise;
}

module.exports = timer;

点击运行。

4: Asynchronous Timer

查看要求：

输入：

function timer() {

    const promise = new Promise(function(resolve, reject) {
        setTimeout(function() {
            resolve('resolve');
        }, 1000);
    });

    return promise;
}

module.exports = timer;

点击运行。

5: Async Await

查看要求：

输入：

const { getResults } = require('./lab');
const { sendResults } = require('./messaging');
const { logResponse, logError } = require('./logs');

async function handleResults(patientId) {
      const res = await getResults(patientId);
      const r = await sendResults(patientId, res);
      await logResponse(r);
}

module.exports = handleResults;

点击运行。

6: Catch Await

查看要求：

输入：

const { getResults } = require('./lab');
const { sendResults } = require('./messaging');
const { logResponse, logError } = require('./logs');

async function handleResults(patientId) {
    try {
        const res = await getResults(patientId);
        const r = await sendResults(patientId, res);
        await logResponse(r);
    } catch (ex) {
        logError(ex);
    }
}

module.exports = handleResults;

点击运行。

Pact: A Promise Library

1: Then and Catch

查看要求：

输入：

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.f1 = (value)=> {
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        this.catchs.push(c);
    }
    then(t) {
        this.thens.push(t);
    }
}

module.exports = Pact;

点击运行。

2: Executor Function

查看要求：

输入：

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.f1 = (value)=> {
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        this.catchs.push(c);
    }
    then(t) {
        this.thens.push(t);
    }
}

module.exports = Pact;

点击运行。

3: Then... What?

查看要求：

输入：

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.f1 = (value)=> {
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        this.catchs.push(c);
    }
    then(t) {
        this.thens.push(t);
    }
}

module.exports = Pact;

点击运行。

4: Catch the Rejection

查看要求：

输入：

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.f1 = (value)=> {
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        this.catchs.push(c);
    }
    then(t) {
        this.thens.push(t);
    }
}

module.exports = Pact;

点击运行。

5: Multiple Callbacks

查看要求：

输入：

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.f1 = (value)=> {
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        this.catchs.push(c);
    }
    then(t) {
        this.thens.push(t);
    }
}

module.exports = Pact;

点击运行。

6: Immediate Resolve

查看要求：

输入：

const STATUS = {
    PENDING: 0,
    RESOLVED: 1,
    REJECTED: 2,
}

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.status = STATUS.PENDING;
        this.f1 = (value)=> {
            this.resolvedValue = value;
            this.status = STATUS.RESOLVED;
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            this.rejectedValue = value;
            this.status = STATUS.REJECTED;
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        if (this.status === STATUS.PENDING) {
            this.catchs.push(c);
        }
        else if (this.status === STATUS.REJECTED) {
            c(this.rejectedValue);
        }
    }
    then(t) {
        if (this.status === STATUS.PENDING) {
            this.thens.push(t);
        }
        else if (this.status === STATUS.RESOLVED) {
            t(this.resolvedValue);
        }
    }
}

module.exports = Pact;

点击运行。

7: Chaining Callbacks

查看要求：

输入：

const STATUS = {
    PENDING: 0,
    RESOLVED: 1,
    REJECTED: 2,
}

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.status = STATUS.PENDING;
        this.f1 = (value)=> {
            this.resolvedValue = value;
            this.status = STATUS.RESOLVED;
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            this.rejectedValue = value;
            this.status = STATUS.REJECTED;
            for (let i = 0; i < this.catchs.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        if (this.status === STATUS.PENDING) {
            this.catchs.push(c);
        }
        else if (this.status === STATUS.REJECTED) {
            c(this.rejectedValue);
        }
    }
    then(t) {
        if (this.status === STATUS.PENDING) {
            return new Pact((resolve, reject) => {
                this.thens.push((val) => {
                    if (val instanceof Pact) {
                        val.then((val) => resolve(t(val)));
                    }
                    else {
                        resolve(t(val));
                    }
                });
            });
        }
        else if (this.status === STATUS.RESOLVED) {
            t(this.resolvedValue);
        }
    }
}

module.exports = Pact;

点击运行。

8: Chaining Promises

查看要求：

输入：

const STATUS = {
    PENDING: 0,
    RESOLVED: 1,
    REJECTED: 2,
}

class Pact {
    constructor(fn) {
        this.catchs = [];
        this.thens = [];
        this.status = STATUS.PENDING;
        this.f1 = (value)=> {
            this.resolvedValue = value;
            this.status = STATUS.RESOLVED;
            for (let i = 0; i < this.thens.length; i++) {
                this.thens[i](value);
            }
        };
        this.f2 = (value)=> {
            this.rejectedValue = value;
            this.status = STATUS.REJECTED;
            for (let i = 0; i < this.catchFn.length; i++) {
                this.catchs[i](value);
            }
        };
        fn(this.f1, this.f2);
    }
    catch(c) {
        if (this.status === STATUS.PENDING) {
            this.catchs.push(c);
        }
        else if (this.status === STATUS.REJECTED) {
            c(this.rejectedValue);
        }
    }
    then(t) {
        if (this.status === STATUS.PENDING) {
            return new Pact((resolve, reject) => {
                this.thens.push((val) => {
                    if (val instanceof Pact) {
                        val.then((val) => resolve(t(val)));
                    }
                    else {
                        resolve(t(val));
                    }
                });
            });
        }
        else if (this.status === STATUS.RESOLVED) {
            t(this.resolvedValue);
        }
    }
}

module.exports = Pact;

点击运行。

以上第三周的课程学习完成。

未完待续……

了解更多，请关注作者：https://twitter.com/bitc2024

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