如何从 Node.js 中的异步函数返回数组？
我们必须从另一个异步或同步的函数中调用异步函数(我们可以传递数组或选择在异步函数本身中声明数组)，然后从异步函数中返回数组。
基本的方法是包含一个 try-catch 块。如果在执行 try block 语句时发生任何错误，则使用 catch 块来处理异常。
例 1: 下面是我们调用打印功能的代码。我们在这个函数中定义数组(在这个例子中是异步的)，把它传递给另一个异步函数排序。排序功能然后对数组进行排序并返回数组，然后我们从打印功能显示数组。
index.js
const sort = async (arr) => {
try {
let i, j, temp;
// Using bubble sort to sort the array
for (i = 0; i < arr.length; i++) {
for (j = i + 1; j < arr.length; j++) {
if (arr[i] > arr[j]) {
// The await prevents the
// execution of next line
// until this line is executed
temp = await arr[i];
arr[i] = await arr[j];
arr[j] = await temp;
}
}
}
// Returns the sorted array
return arr;
}
catch (e) {
// Display the error in case
// enything wrong happened
console.log(e)
}
}
const print = async () => {
// Use try-catch block to handle error
try {
// Define and initialize an array
let arr = [17, 90, 13, 10, 76]
// Call the "sort" function passing
// the array and store the result in
// "sortedArray", await will prevent
// the execution of next line until
// this line is executed.
const sortedArray = await sort(arr)
// Display sortedArray to check if
// everything works fine
console.log(sortedArray)
}
catch (e) {
// Display the error in case
// anything wrong happened
console.log(e)
}
}
// Calling print() is called
print();
使用以下命令运行 index.js 文件:
node index.js
输出:
[ 10, 13, 17, 76, 90 ]
示例 2: 现在让我们看看从异步函数返回数组的示例，该异步函数已在该异步函数中声明。该函数将返回一个由小于给定数 n 的所有素数组成的数组
index.js
const prime = async (N) => {
try {
const arr = []
// Iterate from 2 to N-1 to check
// which numbers are prime
for (var i = 2; i < N; i++) {
let j = 2
while (j < i) {
// Check if the number is
// divisble by any number
// except 1 and itself
if (i % j == 0) {
break
}
j++;
}
if (j == i) {
// If this condition holds
// true then it means that
// the number is not
// divisible by any number
// except 1 and itself.
// Therefore, it is a prime
// number and add this number
// to the array.
arr.push(j)
}
}
// Return the array
return arr
}
catch (e) {
// Display the error in case
// anything wrong happened
console.log(e)
}
}
const findPrime = async () => {
try {
let N = 20
// Call prime() passing argument
// N which is equal to 20 and
// store the result in an array
const primeAry = await prime(N)
// Print the array
console.log(primeAry)
}
catch (e) {
// Display the error in case
// anything wrong happened
console.log(e)
}
}
// Calling findPrime() method
findPrime()
输出:
[
2, 3, 5, 7,
11, 13, 17, 19
]
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