Below, I have written a function that takes an array and a key to search and count the number of times the key matches an element in an array. I am attempting to modify my function to count the number of matches asynchronously but don't know how to best go about it. Any insight or examples would be greatly appreciated.

My Code:

function countMatches(arr, key) 
{ 
    var count=0; 
    var i; 
    for (i=0; i < arr.length; i  ) 
    { 
        if(arr[i] == key) count=count 1; 
    } 
    return count; 
}

let arr1 = [3, 2, 4, 6, 1, 1, 6, 8, 9];
console.log(countMatches(arr1, 6));

CodePudding user response：

Use Promise

function countMatches(arr, key) 
{ 
    return new Promise((resolve) => {
        var count=0; 
        var i; 
        for (i=0; i < arr.length; i  ) 
        { 
            if(arr[i] == key) count=count 1; 
        } 
        resolve(count); 
    });
}

let arr1 = [3, 2, 4, 6, 1, 1, 6, 8, 9];
countMatches(arr1, 6).then(result => console.log(result));

CodePudding user response：

You can return a promise from any synchronous function by converting it to an asynchronous function using the async keyword:

/** This is a sync function */
function getNumber1 () {
  return 42;
}

const n1 = getNumber1();
console.log({sync: n1}); // 42

/**
This is an async function
Notice the `async` keyword before `function`
It automatically returns a promise which resolves to the value
vvvvv                                                       */
async function getNumber2 () {
  return 42;
}

getNumber2().then(n2 => console.log({async: n2})); // 42

CodePudding user response：

async/ await

async function  countMatchesAsync(arr, key) 
{ 
    var count=0; 
    var i; 
    for (i=0; i < arr.length; i  ) 
    { 
        if(arr[i] == key) count=count 1; 
    } 
    return await count; 
}

let arr1 = [3, 2, 4, 6, 1, 1, 6, 8, 9];
countMatchesAsync(arr1, 6).then(console.log);