Google Maps 'data' parameter parser

A JavaScript parser for the Protocol Buffer implementation used for the 'data' parameter in google maps URLs.

Demo test page

See examples of what this library does at the demonstration test page.

Background

Google Maps directions URLs typically look something like this: https://www.google.co.uk/maps/dir/Bonn,+Germany/Berlin,+Germany/@51.6456171,7.9144552,7z/data=!3m1!4b1!4m13!4m12!1m5!1m1!1s0x47bee19f7ccbda49:0x86dbf8c6685c9617!2m2!1d7.0982068!2d50.73743!1m5!1m1!1s0x47a84e373f035901:0x42120465b5e3b70!2m2!1d13.404954!2d52.5200066?hl=en

While the user-specified waypoint inputs (Bonn and Berlin in this example) are named in the path, and the map centre coordinates are specified clearly following the @, other properties, including the actual coordinates of the waypoints, the type of map and the selected mode of transport are encoded in the 'data' parameter in a URL-safe string representation of a 'Protocol Buffer'.

Elements are separated by ! marks. Each element consists of

• an integer id
• a single character alphabetic type
• a string value (whose format appears to vary according to the type, but is assumed to be composed of alphanumeric and URL-safe characters)

The meaning of an element depends on these properties, as well as the element's place in the tree.

Dependencies

• jquery

Functionality

The parser extracts the data parameter and forms it into a tree of nodes, each representing one of the elements in the Protocol Buffer.

Usage

Creation

var parsedProtocolBuffer = PrBufNode.create(url);

Traversal

for (directChild of parsedProtocolBuffer.getChildren()) {
    console.log(directChild.id(),
                directChild.type(),
                directChild.value());
}