Ways to transform a foreach loop into a promise-based operation

Question

Ways to transform a foreach loop into a promise-based operation

I have a function that recursively deletes nodes:

removeNode(data.toString())
function removeNode(node){
    Item.findByIdAndDelete(node).then(()=>{
        Item.find({parent: mongoose.Types.ObjectId(node)}).select('_id').then((nodes)=>{
            nodes.forEach(n => {
                removeNode(n._id)
            });
        })
    })
}

I want to convert this function into a promise so I can use it like this:

removeNode(data.toString()).then(()=>{console.log('deletion complete')})

Any suggestions on how I can achieve this promisification would be highly appreciated!

javascript loops asynchronous promise

Answer 1

Answer №1

Best Practices:

Make sure to return every promise created within a callback function.
Utilize map instead of forEach when dealing with arrays of promises from recursive calls, and pass the resulting array to Promise.all.
Simplify the promise chain by avoiding nested then callbacks.

function remove(node) {
    return Item.findByIdAndDelete(node).then(() => {
        return Item.find({parent: mongoose.Types.ObjectId(node)}).select('_id');
    }).then(d => {
        return Promise.all(d.map(e => {
            return remove(e._id)
        }));
    });
}

Consider using async await for improved readability:

async function remove(node) {
    await Item.findByIdAndDelete(node);
    let d = await Item.find({parent: mongoose.Types.ObjectId(node)}).select('_id');
    return Promise.all(d.map(e => remove(e._id)));
}

Answer 2

Best Practices:

Make sure to return every promise created within a callback function.
Utilize map instead of forEach when dealing with arrays of promises from recursive calls, and pass the resulting array to Promise.all.
Simplify the promise chain by avoiding nested then callbacks.

function remove(node) {
    return Item.findByIdAndDelete(node).then(() => {
        return Item.find({parent: mongoose.Types.ObjectId(node)}).select('_id');
    }).then(d => {
        return Promise.all(d.map(e => {
            return remove(e._id)
        }));
    });
}

Consider using async await for improved readability:

async function remove(node) {
    await Item.findByIdAndDelete(node);
    let d = await Item.find({parent: mongoose.Types.ObjectId(node)}).select('_id');
    return Promise.all(d.map(e => remove(e._id)));
}

Ways to transform a foreach loop into a promise-based operation

Answer №1

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