未捕获的 SyntaxError：await 仅在异步函数中有效（FireBase 文档）

Question

I'm trying to get data from my Firestore database. Based on Firestore documentation I wrote this:

const productsRef = db.collection('products');
const snapshot = await productsRef.get();
snapshot.forEach(doc => {
  console.log(doc.id, '=>', doc.data());
});

I get the error in the title. Why do they share a code that doesn't work or am I missed something? Thank you!

Answer 1

You need a async function in order to use the await keyword.
If you don't have a function in wich this code is ran you can use an IIFE wrapper

(async ()=>{
  const productsRef = db.collection('products');
  const snapshot = await productsRef.get();
  snapshot.forEach(doc => {
    console.log(doc.id, '=>', doc.data());
  });
})();

or don't use await at all and handle it into the then chain :

const productsRef = db.collection('products');
const snapshot = productsRef.get().then((snapshot)=>{
  snapshot.forEach(doc => {
    console.log(doc.id, '=>', doc.data());
  });
});

Answer 2

The await keyword is used for consuming promises, along with async . But in order for await to work you must wrap it inside a function declared with the async keyword, like so:

const getProducts = async () => {
  const productsRef = db.collection('products');
  const snapshot = await productsRef.get();
  snapshot.forEach(doc => {
    console.log(doc.id, '=>', doc.data());
  });
}

getProducts();