JS fragment to zoom a Leaflet JS map to fit all points

leaflet-fit-points.js

    function fitBounds(map, initialBounds, fitOptions) {
        var bounds = new L.LatLngBounds(),
            options = {reset: true};

        if (typeof(fitOptions) == 'undefined' && initialBounds && !initialBounds.getCenter) {
            fitOptions = initialBounds;
            initialBounds = null;
        }

        if (initialBounds) {
            bounds.extend(initialBounds);
        }

        if (fitOptions) {
            $.extend(options, fitOptions);
        }

        map.eachLayer(function (layer) {
            if (layer.getLatLng) {
                bounds.extend(layer.getLatLng());
            }
        });

        if (bounds && bounds.isValid()) {
            map.fitBounds(bounds, options);
        } else {
            map.fitWorld(options);
        }
    }