Node JS async module initialization patterns

Question

I need to asynchrounisly get some data during module startup and save returned value as top level variable. And other methods of module should not be called before this variable has been initialized.

So basically I need something like this:

myModule.js
===========

// i can't use await here...
const importantData = await fetch('/my-service'); 

exports.myMethod = function () {
    // do something with importantData
}

So,

Top level importantData is promise
If someone call myMethod method then it should defer it's execution until top level const is resolved
I don't want to use let

What is the elegant way to sove this problem?

Thanks

Make every exported function an async function that internally awaits the resolution of the initialization fetch. — Jared Smith
– Jared Smith, Commented May 28, 2018 at 22:38

Paul · Accepted Answer · 2018-05-28 22:39:36Z

2

You will need to make myMethod asynchronous:

const importantDataPromise = fetch('/my-service'); 

exports.myMethod = async function () {
    const importantData = await importantDataPromise;
    ... // Do stuff with importantData.
}

answered May 28, 2018 at 22:39

Paul

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