Layers

Layers provide a way to style and organize the markers associated with source records. Markers can be targeted using attributes and values defined in the records.

Creating a Layer

To create a layer, click the New Layer button

Editing a Layer

Title

The layer title can be any arbitrary string of text and is only used in the UI

Target

The layer target is a JavaScript expression which should evaluate to either true or false. Upon saving a layer, the target is evaluated against every source record in order to associate records with the layer.

The constant record is exposed to the target expression and can be used to filter records based on source data. For example, lets say this is what our source records look like (represented as a table to save space):

// Matches records where Grade is equal to 1. (2 records)
record['Grade'] == '1'

// Matches records where School is equal to THE. (3 records)
record['School'] == 'THE'

// Matches records where Grade is equal to 1, 2, or 3. (5 records)
['1','2','3'].includes(record['Grade'])

// Matches records where School is equal to LRE. (0 records)
record['School'] == 'LRE'

Children

Layers can nested by dragging and dropping them in to the parent layer's children container.

Child layers: Inherit their parent's style settings Inherit their parent's visibility Evaluate their target filter only against records that are also matched by their parent Are deleted when their parent is deleted