Feature request: search(bbox, dataString)

[maja42]

The entries/nodes I store in RBush have many properties, including an 'id' field.
When performing a search-query, I only need a list of ids, rather than a list of entries.

To do so, I currently use the map function:

var entries = tree.search(bbox);
var ids = entries.map(function(val) {
    return val.id;
});

For my specific case, it would be nice if RBush could offer this functionality for me, so that I don't need to convert the result myself anymore. (Note: changing the result.push(child); into an result.push(child.id); in rbush's search method does the trick.)

To do this, the search-function could take a second, optional parameter where I can pass the string ".id". This would work similar to the constructor method that accepts a format (and which is awesome!).

However, I'm not sure if there is enough demand for this feature and if it makes sense to put it into RBush.

[Volodymyr Agafonkin]

Thanks for the suggestion! However, I don't think it's worth complicating the API with additional options if you can simply call entries.map(p => p.id), which is simple and straightforward.