Utilizing LocalForage's asynchronous `getItem()` method involves awaiting the retrieval of two variables before completing the loading process

Question

Utilizing LocalForage's asynchronous `getItem()` method involves awaiting the retrieval of two variables before completing the loading process

I'm still getting the hang of working with asynchronous Javascript calls and handling promises. It's a shift from my usual mindset of Do This, Wait for This.

Currently, I'm utilizing localforage on my website and need to retrieve data from two different sources.

var ordersRaw = null
var itemsRaw = null
localforage.getItem('ordersRaw').then((res) => {
    if(res) {
        ordersRaw = res
    } 
})
localforage.getItem('itemsRaw').then((res) => {
    if(res) {
        itemsRaw = res
    } 
})
if(ordersRaw && itemsRaw) {
    // Ready to load the screen
} else { console.log('NO DATA') }

Once I have both sets of data, I want to finish loading the screen by executing a function.

displayWithResults()

The challenge arises when running this code because of its async nature, causing the 'NO DATA' message to appear prematurely.

I find myself constantly facing this dilemma in Javascript and haven't completely mastered it yet. Any insights or tips would be greatly appreciated.

javascript asynchronous async-await local-storage localforage

Answer 1

Answer №1

Here are a few solutions for tackling this issue:

Implement nested callbacks
Utilize async await with promises
Organize results under a single key within an object
Use Promise.all method

The key is to fetch all results asynchronously prior to the evaluation process.

I recommend utilizing async await for cleaner code implementation.

You can implement it in the following way:

(async() => {
    try {
        const ordersRaw = await localforage.getItem('ordersRaw');
        const itemsRaw = await localforage.getItem('itemsRaw');
        if(ordersRaw && itemsRaw) {
            // Proceed to load the screen
        } else { 
           console.log('NO DATA') }
        }
    } catch (e) {
        console.log(e);
    }
})();

Edit: The above code runs sequentially. Consider replacing it with something like:

const getOrders = localforage.getItem('ordersRaw');
const getItems = localforage.getItem('itemsRaw');
const [ordersRaw, itemsRaw] = await Promise.all([getorders, getItems]);

Answer 2

Here are a few solutions for tackling this issue:

Implement nested callbacks
Utilize async await with promises
Organize results under a single key within an object
Use Promise.all method

The key is to fetch all results asynchronously prior to the evaluation process.

I recommend utilizing async await for cleaner code implementation.

You can implement it in the following way:

(async() => {
    try {
        const ordersRaw = await localforage.getItem('ordersRaw');
        const itemsRaw = await localforage.getItem('itemsRaw');
        if(ordersRaw && itemsRaw) {
            // Proceed to load the screen
        } else { 
           console.log('NO DATA') }
        }
    } catch (e) {
        console.log(e);
    }
})();

Edit: The above code runs sequentially. Consider replacing it with something like:

const getOrders = localforage.getItem('ordersRaw');
const getItems = localforage.getItem('itemsRaw');
const [ordersRaw, itemsRaw] = await Promise.all([getorders, getItems]);

Utilizing LocalForage's asynchronous `getItem()` method involves awaiting the retrieval of two variables before completing the loading process

Answer №1

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