マンガでわかるJavaScriptのPromise

const timer = (time, type) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            if (type === 'resolve') {
                resolve(`${time} 解決`);
            }
            if (type === 'reject') {
                reject(`${time} 拒否`);
            }
        }, time);
    });
};

    

timer(500, 'resolve')
.then(res => {
    console.log('then:', res);
})
.catch(res => {
    console.log('catch:', res);
})
.finally(() => {
    console.log('finally: 終了');
});

    

then: 500 解決
finally: 終了

    

timer(500, 'reject')
.then(res => {
    console.log('then:', res);
})
.catch(res => {
    console.log('catch:', res);
})
.finally(() => {
    console.log('finally: 終了');
});

    

catch: 500 拒否
finally: 終了