Examples
buffer polygons
Select Factor:

This example loads a map of Africa using the "AFRICA" key.

The "AFRICA" map was created using the Mapzania MapStyler (see www.mapzania.com/manual/concepts-mapstyler).

The example uses the "usingLayer" method of the Mapzania Map object to get a "COUNTRIES" Layer Object and make chained calls to the "bufferGeometry" and then the "update" method of the layer to filter and redraw the layer data.

For more on layers see: www.mapzania.com/manual/concepts-layers

For more on the Layer Object and applicable methods see:

var map;

window.onload = function () {
    map = new Mapzania.Map("map-div", "AFRICA");
};

function filterClicked() {

    var el = document.getElementById('filters-select');
    var factor = el.options[el.selectedIndex].text;

    map.usingLayer("COUNTRIES")
        .clearFilters()
        .bufferGeometry(factor)
        .update();
}
#button-div {
    z-index: 1000000;
    position: absolute;
    top: 10px;
    right: 10px;
    border: solid 1px #aaa;
    background-color: white;
    padding: 5px;
    padding-left: 10px;
    padding-right: 10px;
    border-radius: 6px;
}

#map-div {
    position: absolute;
    top: 0px;
    left: 0px;
    bottom: 0px;
    right: 0px;
}
<div id="map-div"></div>

<div id="button-div">
    <span>Select Factor:</span>

    <select id="filters-select">
        <option>0</option>
        <option>-3.0</option>
        <option>-2.0</option>
        <option>-1.0</option>
        <option>1.0</option>
        <option>2.0</option>
        <option>3.0</option>
    </select>

    <button onclick="filterClicked()">Buffer!</button>
</div>