异步迭代数组元素

Question

I'm trying to iterate asynchronously over list of array elements, but with this code:

const calculate = async ({ id, priority, database, product }) => {
    let list_of_products;
    if (priority) {
        list_of_products = await getPriorityList(database, id);
    }
    else {
        const prods = product.split(',');
        await prods.forEach((prod) => {
            list_of_products = getList(database, prod);
            console.log({ list_of_products });
        });
    }
};

I get the following console.log() :

{ list_of_products : Promise { <pending> } }

And of course, an error gets thrown eventually.

What is the best practice to handle async calls when iterating? The getList() method is async as well.

Answer 1

do not use async await in forEach loops. await prods.forEach((prod) . instead of forEach loop you can use for...of loop. checkout this: Using async/await with a forEach loop

you need to add await keyword in front of your getList(database, prod) . otherwise, that async function will return a promise.

I refactored your code.

const calculate = async ({ id, priority, database, product }) => {
    let list_of_products;
    if (priority) {
        list_of_products = await getPriorityList(database, id);
    }
    else {
        const prods = product.split(',');
        for(let prod of prods) {
            list_of_products = await getList(database, prod);
            console.log({ list_of_products });
        }
    }
};