Node.js 如何异步函数返回一个数组

我们必须从另一个函数中调用异步函数，该函数可以是异步的或同步的（我们可以传递数组或选择在异步函数中声明数组），然后从异步函数中返回数组。

基本方法是包含一个try-catch块。如果在执行try块语句时发生任何错误，则使用catch块来处理异常。

示例1： 下面是调用打印函数的代码。我们在该函数中定义数组（在此示例中为异步），将其传递给另一个异步函数sort。sort函数然后对数组进行排序并返回数组，然后我们从打印函数中显示数组。

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 
        // anything 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： 现在让我们来看一个示例，这个示例展示了从一个已在该异步函数中声明的异步函数中返回一个数组。该函数将返回一个小于给定数字N的所有质数的数组。

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  
                // divisible 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 
]