如何为NodeJs中的方法设置时间限制？

Question

I have a use case, where I am doing an external API call from my code,
The response of the external API is required by my code further on

I am bumping into a scenario, where the external API call at times takes far too long to return a response,
casing my code to break, being a serverless function

So I want to set a time limit to the external API call,
Where if I don't get any response from it within 3 secs, I wish the code to gracefully stop the further process

Following is a pseudo-code of what I am trying to do, but couldn't figure out the logic -

let test = async () => {
    let externalCallResponse = '';

    await setTimeout(function(){ 

        //this call sometimes takes for ever to respond, but I want to limit just 3secs to it
        externalCallResponse = await externalCall();
    }, 3000);

    if(externalCallResponse != ''){
        return true;
    }
    else{
        return false;
    }
}

test();

Reference -
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/SSM.html#getParameters-property
I'm using AWS SSM's getParameters method

Answer 1

You cannot await setTimeout as it doesn't returns a Promise .

You could implement a function that returns a Promise which is fulfilled after 3 seconds.

function timeout(seconds) {
   return new Promise((resolve) => {
       setTimeout(resolve, seconds * 1000)
   });
}

You can await the above function in your code passing the number of seconds you want to wait for

let test = async () => {
    let externalCallResponse = ''; 
    
    setTimeout(async () => {
       externalCallResponse = await externalCall();
    }, 0);

    await timeout(3); // wait for 3 seconds 

    if(externalCallResponse != '') return true;
    else return false;
}

Following code snippet demonstrates the usage of timeout function written above. It mocks a api request that returns a response after 4 seconds.

 function timeout(seconds) { return new Promise(resolve => { setTimeout(resolve, seconds * 1000); }); } function apiRequest() { return new Promise(resolve => { setTimeout(() => resolve('Hello World'), 4000); }); } let test = async () => { let externalCallResponse = ''; setTimeout(async () => { externalCallResponse = await apiRequest(); }, 0); await timeout(3); // wait for 3 seconds if (externalCallResponse;= '') return true; else return false; }. test().then(res => console.log(res)).catch(err => console.log(err;message));

Answer 2

You could do something like this:

const timeout = async (func, millis) => {
   return new Promise(async (resolve, reject) => {
      setTimeout(() => reject(), millis);

      resolve(await func());
   });
}

timeout(() => doStuff(), 3000)
   .then(() => console.log('worked'))
   .catch(() => console.log('timed out'));

Tests:

 const timeout = async (func, millis) => { return new Promise(async (resolve, reject) => { setTimeout(() => reject(), millis); resolve(await func()); }); } const doStuffShort = async () => { // Runs for 1 second return new Promise((resolve) => setTimeout(() => resolve(), 1000)); } const doStuffLong = async () => { // Runs for 5 seconds return new Promise((resolve) => setTimeout(() => resolve(), 5000)); } timeout(() => doStuffShort(), 3000).then(() => console.log('1 worked')).catch(() => console.log('1 timed out')); timeout(() => doStuffLong(), 3000).then(() => console.log('2 worked')).catch(() => console.log('2 timed out'));

Answer 3

you can use something like this, I created a function that return a promise then I used this promise.

let test = async () => {

    return promiseTimeout()
}

const promiseTimeout = () => {
    return new Promise(async (resolve, reject) => {
        setTimeout(function () {
            let externalCallResponse=""
            externalCallResponse = await externalCall();
            if (externalCallResponse != '') {
                return resolve(true);
            }
            else {
                return resolve(false);
            }
        }, 3000);
    })
}

test().then(result=>{
    console.log(result);
});