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Google Maps Mile Markers JavaScript
Personal JavaScript / Google Maps programming example, still in alpha.
Live at:
https://c9.io/bradhenslee/gmaps-mile-markers/workspace/map.html
The Google Maps API does not include methods for numbered markers or placing evenly spaced markers along a route (such as mile/kilometer markers).
Using the computeDistanceBetween() and interpolate() methods in the google.maps.geometry.spherical library, this script traverses all nodes of a given polyline and returns an array of equally spaced marker postions.
Numbered marker icons are achieved by use of the Google Chart API (which is a bit slow).