new DocumentChange()
A DocumentChange represents a change to the documents matching a query. It contains the document affected and the type of change that occurred.
Members
doc
The document affected by this change.
Example
```
let query = firestore.collection('col').where('foo', '==', 'bar');
let unsubscribe = query.onSnapshot(querySnapshot => {
for (let change of querySnapshot.docChanges) {
console.log(change.doc.data());
}
});
// Remove this listener.
unsubscribe();
```newIndex
The index of the changed document in the result set immediately after this DocumentChange (i.e. supposing that all prior DocumentChange objects and the current DocumentChange object have been applied). Is -1 for 'removed' events.
Example
```
let query = firestore.collection('col').where('foo', '==', 'bar');
let docsArray = [];
let unsubscribe = query.onSnapshot(querySnapshot => {
for (let change of querySnapshot.docChanges) {
if (change.oldIndex !== -1) {
docsArray.splice(change.oldIndex, 1);
}
if (change.newIndex !== -1) {
docsArray.splice(change.newIndex, 0, change.doc);
}
}
});
// Remove this listener.
unsubscribe();
```oldIndex
The index of the changed document in the result set immediately prior to this DocumentChange (i.e. supposing that all prior DocumentChange objects have been applied). Is -1 for 'added' events.
Example
```
let query = firestore.collection('col').where('foo', '==', 'bar');
let docsArray = [];
let unsubscribe = query.onSnapshot(querySnapshot => {
for (let change of querySnapshot.docChanges) {
if (change.oldIndex !== -1) {
docsArray.splice(change.oldIndex, 1);
}
if (change.newIndex !== -1) {
docsArray.splice(change.newIndex, 0, change.doc);
}
}
});
// Remove this listener.
unsubscribe();
```type
The type of change ('added', 'modified', or 'removed').
Example
```
let query = firestore.collection('col').where('foo', '==', 'bar');
let docsArray = [];
let unsubscribe = query.onSnapshot(querySnapshot => {
for (let change of querySnapshot.docChanges) {
console.log(`Type of change is ${change.type}`);
}
});
// Remove this listener.
unsubscribe();
```Methods
isEqual(other)
Returns true if the data in this DocumentChange is equal to the provided
value.
Parameters:
| Name | Type | Description |
|---|---|---|
other |
* |
The value to compare against. |
Returns:
| Type | Description |
|---|---|
|
true if this |