async/await如何與forEach一起使用？

Question

如何使用async/await來實現以下目標？

self.onmessage = event => { 

    // async stuff in forEach needs to finish 
    event.data.search.split(',').forEach((s, i) => { 
    db.get('customers').then(doc => { 
     ... 
    }) 
    }) 

    // before getting here 
} 

Answer 1

您需要使用Promise.all與Array#map更換您到Array#forEach電話：

self.onmessage = async (event) => { 

    // async stuff in forEach needs to finish 
    await Promise.all(event.data.search.split(',').map((s, i) => { 
    return db.get('customers').then(doc => { 
     ... 
    }) 
    })) 

    console.log('All finished!') 

}