Sort array based on string transformed into date-CodePudding

So I have an array containing reviews (which I retrieve from firebase firestore). The field 'date' is string in firestore. How can I sort the reviews in descending order based on this date? I have tried this but they are in the retrieval order.

const getReviews=async()=>{
        let reviewsClone=[];
        const q = query(collection(db, "reviews"), where("product", "==", uniqueProductName.product));
        const querySnapshot=await getDocs(q);
        querySnapshot.forEach((doc)=>{
            reviewsClone.push(doc.id);
        })

        reviewsClone.sort(function(a,b){
            return new Date(a.date) - new Date(b.date);
          });
        setReviews(reviewsClone);

    }

Thank you in advance.

CodePudding user response：

Could you try this? It's likely that you are sorting an array of strings reviewsClone currently, which all have .date prop undefined, therefore .sort has no effect.

const getReviews=async()=>{
        let reviewsClone=[];
        const q = query(collection(db, "reviews"), where("product", "==", uniqueProductName.product));
        const querySnapshot=await getDocs(q);
        querySnapshot.forEach((doc)=>{
            reviewsClone.push(doc);
        })

        reviewsClone.sort(function(a,b){
            return new Date(a.date) - new Date(b.date);
          });
        setReviews(reviewsClone.map(c => c.id));

    }

CodePudding user response：

Assuming that all the data is valid, and contains the date key. Your sort function is incorrect. To sort in descending order, your sort function should look like this:

reviewsClone.sort(function(a,b){
        return new Date(b.date) - new Date(a.date);
      });

This documentation should be helpful.