JavaScript笔记 #06# Promise简单例子

// 辅助函数
const randomBoolean = () => {
    return Math.random() < 0.5;
};

// 客户对象，处理找书的结果
const customer = {
    dealWithResult: function(success) {
        if(success) {
            console.log(‘customer：去书店取书‘);
        } else {
            console.log(‘customer：有空去别的书店问问‘);
        }
    }
}

// 书店老板对象，提供一个异步的找书方法。
const bossOfBookstore = {
    askForBook: function(bookName, phoneNumber) {
        setTimeout((phoneNumber) => {
            let result = randomBoolean();
            console.log(‘bossOfBookstore：‘ + (result ? ‘找到书了‘ : ‘没有这本书‘));
            customer.dealWithResult(result);
        }, 3000);
    }
}

//debugger;
bossOfBookstore.askForBook(‘七龙珠‘, 15298000122);
// → bossOfBookstore：没有这本书
// → customer：有空去别的书店问问 

// 辅助函数
const randomBoolean = () => {
    return Math.random() < 0.5;
};

// 客户对象，处理找书的结果
const customer = {
    dealWithResult: function(success) {
        if(success) {
            console.log(‘customer：去书店取书‘);
        } else {
            console.log(‘customer：有空去别的书店问问‘);
        }
    }
}

// 书店老板对象，提供一个异步的找书方法。
const bossOfBookstore = {
    askForBook: function(bookName, phoneNumber) {
        return new Promise(resolve => {
            setTimeout(phoneNumber => {
                let result = randomBoolean();
                console.log(‘bossOfBookstore：‘ + (result ? ‘找到书了‘ : ‘没有这本书‘));
                resolve(result); // 书店老板才不关心你怎么处理的！    
            }, 3000);            
        });
    }
}

bossOfBookstore.askForBook(‘某某书‘, 15298000122).then(result => {
    customer.dealWithResult(result);
});

// 辅助函数
const randomBoolean = () => {
    return Math.random() < 0.5;
};

// 客户对象，处理找书的结果
const customer = {
    dealWithResult: function(success) {
        if(success) {
            console.log(‘customer：去书店取书‘);
        } else {
            console.log(‘customer：有空去别的书店问问‘);
        }
    }
}

// 书店老板对象，提供一个异步的找书方法。
const bossOfBookstore = {
    askForBook: function(bookName, phoneNumber) {
        return new Promise((resolve, reject) => {
            setTimeout(phoneNumber => {
                let result = randomBoolean();
                console.log(‘bossOfBookstore：‘ + (result ? ‘找到书了‘ : ‘没有这本书‘));
                if (result) {
                    resolve(true);
                } else {
                    reject(false);
                }
            }, 500);            
        });
    }
}

// 写法一
bossOfBookstore.askForBook(‘某某书‘, 15298000122).then(result => {
    customer.dealWithResult(result);
}).catch(result => { 
    customer.dealWithResult(result);
});

// 写法二
bossOfBookstore.askForBook(‘某某书‘, 15298000122).then(result => {
    customer.dealWithResult(result);
}, result => { 
    customer.dealWithResult(result);
});