Function to decode an encoded polyline for JavaScript

polyline-decode.js

function decodePolyline(encoded) {

    var points = []
    var index = 0,
        len = encoded.length;
    var lat = 0,
        lng = 0;
    while (index < len) {
        var b, shift = 0,
            result = 0;
        do {

            b = encoded.charAt(index++).charCodeAt(0) - 63; //finds ascii                                                                                    //and substract it by 63
            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.charAt(index++).charCodeAt(0) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        var dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
        lng += dlng;

        points.push({
            latitude: (lat / 1E6),
            longitude: (lng / 1E6)
        })

    }
    return points
}