[SOLVED] Schedule an async function in NodeJS

Issue

I want to schedule a function which is asynchronous (async/await ruturn type) to run for every two minutes.

I tried with generic setInterval, node modules like node-schedule , cron, node-cron, async-poll but unable to achieve polling for a async function call.

This is what I tried in code:

cron.schedule("*/2 * * * *", await this.servicesManager.startPoll() => {
               console.log('running on every two minutes');
}); // this is not working breaks after first run
            
const job = schedule.scheduleJob(" */1 * * * *", async function() {
   try {
         return await this.ServicesManager.startPoll(); // this function startPoll is undefined when using this 
       } catch (e) {
         console.log(e);
   }
   console.log('Run on every minute');
});
                    
const event = schedule.scheduleJob("*/2 * * * *", this.ServicesManager.startPoll()); //using node-schedule , breaks after first time
cron.schedule("*/2 * * * *", await this.ServicesManager.startPoll()); // using cron same result as using node-schedule
return await this.ServicesManager.startPoll(); // without polling works

Solution

Try something like this

// version 1
cron.schedule("*/2 * * * *", this.servicesManager.startPoll);

// version 2 => if servicesManager needs its `this` reference
cron.schedule("*/2 * * * *", async () => this.servicesManager.startPoll());

//version 3 ==> using node-schedule
schedule.scheduleJob("*/1 * * * *", async () => this.ServicesManager.startPoll());

I don't know about your servicesManager, you might have to use "version 2" from above to get it to work.

The schedule libraries need a function to execute, but instead they get a resolved Promise in the examples above.

Answered By - kraf

Answer Checked By - Katrina (WPSolving Volunteer)