Firestore 查询文档以特定字符开头

Question

Is it possible to query a firestore collection to get all document that starts with a specific character? For example if I have a collection "Items" that contains:

I want for example only the document starting with II don't know how modify the query, the method charAt[0] is not recognized:

return itemRef
      .doc(this.itemsId)
      .collection("october")
      .where(firebase.firestore.FieldPath.documentId().charAt[0], "==", randomChar)

Answer 1

From the top of my head, if interested in the letter "I":

var lower = 'I';
var upper = String.fromCharCode(lower.codeUnitAt(0) + 1);

itemRef
      .doc(this.itemsId)
      .collection("october")
      .where(firebase.firestore.FieldPath.documentId() ">=", lower)
      .where(firebase.firestore.FieldPath.documentId() "<", upper)

Not sure, what happens in case of the letter Z.