javascript/Typescript 在 .then 内返回 array.filter 内的回调

Question

I want to filter an array but to do that I need to call my database that returns a promise. Code:

this.arrayToFilter.filter(myObject => {
    this.dataBaseService.getSomething(myObject.id).then(something => {
        // some calculations
        return shouldBeFiltered 
    })
})

How can I get the value of shouldBeFiltered to the filter callback?

Answer 1

Make an array of Promises and call Promise.all on it before filtering:

const shouldBeFilteredArr = await Promise.all(
  this.arrayToFilter.map(({ id }) => this.dataBaseService.getSomething(id)
);
const filteredItems = this.arrayToFilter.filter((myObject, i) => {
  const something = shouldBeFilteredArr[i];
  // some calculations
  return shouldBeFiltered;
});