在Promise中使用for循环

Question

I am having a scenario where Step 1: i have run a loop and push the data into an array step 2: once my first loop is complete I will start second loop to push data into the same array

I have tried async function, this is my example use case

  var arr =[]; //declared globally
    async function myloop(){

    for(i=0;i<10;i++){
    arr.push(i);
    }

    }

   // Here is what I wanna do now
    myloop().then(function(){
    for(i=10;i<20;i++){
    arr.push(i)
    }
    })

I have to wait until my function pushes all the data in the loop, after loop completion I need to come back here for second run

Answer 1

The context is a bit unclear, but I assume that you are receiving two arrays from two collections, which returns the array in a Promise .

Let's suppose you have these two functions.

function dataBaseCallX() {
    // returns a Promise<Array>
}

function dataBaseCallY() {
    // returns a Promise<Array>
}

And you want to combine both the results right? Then here you can use the async-await feature. I think this is what you want.

const resultA = await dataBaseCallX();  // An Array
const resultB = await dataBaseCallY();  // An Array

let combinedResults = resultA.concat(resultB);

If in case of errors, you can simply wrap this into a try catch block.