是否可以将字符串数组与 Promise<string[]> 连接以在 typescript/javascript 中返回 Promise<String[]>？答案

【问题标题】：Is it possible to concat string array with Promise<string[]> to return Promise<String[]> in typescript/javascript?是否可以将字符串数组与 Promise<string[]> 连接以在 typescript/javascript 中返回 Promise<String[]>？
【发布时间】：2020-12-21 23:00:13
【问题描述】：

public async getPromiseArray(from: number, to: number): Promise<String[]> {
    const someArray = this.someArray;
    const arr1 = someArray.slice(from, from + 2); // This returns an array of string
    const arr2 = this.storageService.get(from + 3, to) // This returns Promise<String[]>

    // Is is possible to return a promise<String[]> which is a concat of arr1 and arr2
}

我可以等待 arr2 并返回字符串数组，但是可以直接从这个方法返回 Promise 吗？

【问题讨论】：

实际上没有什么是异步的。您可以返回一个包装您的字符串的承诺，但该字符串的处理已经发生并且承诺已经解决。
return [...arr1, ...(await arr2)]

标签： javascript typescript promise

【解决方案1】：

试试这个...?

public async getPromiseArray(from: number, to: number): Promise<String[]> {
    try {
        const someArray = this.someArray;
        const arr1 = someArray.slice(from, from + 2);
        const arr2 = await this.storageService.get(from + 3, to);
       resolve(arr1.concat(arr2))
    }
    reject(arr1.concat(arr2))
}

【讨论】：

【解决方案2】：

是的！

只需.then 你的承诺，然后在那里连接：

//If you return a promise and don't use `await`, then there's no need for `async`
public getPromiseArray(from: number, to: number): Promise<String[]> {
    const someArray = this.someArray;
    const arr1 = someArray.slice(from, from + 2); // This returns an array of string
    const arr2 = this.storageService.get(from + 3, to) // This returns Promise<String[]>

    // Is is possible to return a promise<String[]> which is a concat of arr1 and arr2
    return arr2.then(arr2 => arr1.concat(arr2))
}

【讨论】：