Creates filtering function for features


211.0.03 years ago3 years agoMinified + gzip package size for @maptalks/feature-filter in KB




Filter expressions are used to target specific data in a layer. This library implements the semantics specified by the Mapbox GL JS spec.



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.


parameter type description
filter Array mapbox gl filter

Returns Function, filter-evaluating function


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 = [
    ["==", "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);

If you find any bugs or have a feature request, please open an issue on github!

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