decodePolyline.js

function decodePolyline(encoded) {
        if (!encoded) {
            return [];
        }
        var poly = [];
        var index = 0, len = encoded.length;
        var lat = 0, lng = 0;

        while (index < len) {
            var b, shift = 0, result = 0;

            do {
                b = encoded.charCodeAt(index++) - 63;
                result = result | ((b & 0x1f) << shift);
                shift += 5;
            } while (b >= 0x20);

            var dlat = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
            lat += dlat;

            shift = 0;
            result = 0;

            do {
                b = encoded.charCodeAt(index++) - 63;
                result = result | ((b & 0x1f) << shift);
                shift += 5;
            } while (b >= 0x20);

            var dlng = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
            lng += dlng;

            var p = {
                latitude: lat / 1e5,
                longitude: lng / 1e5,
            };
            poly.push(p);
        }
        return poly;
    }