DocumentChange

DocumentChange

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 DocumentChange is equal to the provided value.