Package Exports
- feature-filter
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Readme
Filter
Filter expressions are used to target specific data in a layer. This library implements the semantics specified by the Mapbox GL JS spec.
API
featureFilter(filter)
Given a filter expressed as nested arrays, return a new function that evaluates whether a given feature (with a .properties or .tags property) passes its test.
Parameters
| parameter | type | description |
|---|---|---|
filter |
Array | mapbox gl filter |
Returns Function, filter-evaluating function
Usage
var ff = require('feature-filter');
// will match a feature with class of street_limited,
// AND an admin_level less than or equal to 3,
// that's NOT a polygon.
var filter = [
"all",
["==", "class", "street_limited"],
["<=", "admin_level", 3],
["!=", "$type", "Polygon"]
]
// will match a feature that has a class of
// wetland OR wetland_noveg.
// ["in", "class", "wetland", "wetland_noveg"]
// testFilter will be a function that returns a boolean
var testFilter = ff(filter);
// Layer feature that you're testing. Must have type
// and properties keys.
var feature = {
type: 2,
properties: {
class: "street_limited"
admin_level: 1
}
};
// will return a boolean based on whether the feature matched the filter
return testFilter(feature);