使用 Promise.all 存储不同类型数据的最佳方法是什么？

Question

population: {[id: number]} = {}
places: {[id: string]} = {}

const promises = ['/api/population',
            '/api/data/Country',
            '/api/data/State', 
            '/api/data/County']
             .map(api => fetch(api)

/api/population should be stored in variable population .

Country, State and County should be stored in places .

I would like to store the data in its corresponding variable, what is the best way to do this using Promise.all(). How can I do this with foreach?

Answer 1

Promise.all resolves with an array of its results wherein each result corresponds positionally to the input promise which resolved with it.

The most convenient way to assign the results to distinct identifiers is to use JavaScript's array destructuring syntax.

With async / await

const [populations, countries, states, counties] = await Promise.all([
   '/api/population',
   '/api/data/Country',
   '/api/data/State',
   '/api/data/County'
].map(api => fetch(api)));

With .then

Promise.all([
   '/api/population',
   '/api/data/Country',
   '/api/data/State',
   '/api/data/County'
].map(api => fetch(api)))
  .then(([populations, countries, states, counties]) => { });

To assign to identifiers that have already been declared, you can write

[populations, countries, states, counties] = await Promise.all([
   '/api/population',
   '/api/data/Country',
   '/api/data/State',
   '/api/data/County'
].map(api => fetch(api)));