How to get DataSource length in native-native?

Question

How to get DataSource length in ListView?

Suppose I have the following declaration:

const ds = new ListView.DataSource({ rowHasChanged });
...
someObjectsDs = ds.cloneWithRows(someObjectsArray);

I tried someObjects.length, but it brings me back undefined.

Answer 1

You can view the number of rows to display by calling

someObjectsDs.getRowCount()

Official documentation

Answer 2

You can either dig into the data source object to find the data and grab the length, or you can set the data as a component property and refer to this:

this.someObjectsArray = someObjectsArray;
someObjectsDs = ds.cloneWithRows(this.someObjectsArray);

Now you can do it this.someObjectsArray.length, just be sure to update this variable anytime you update the data source.