Question

What version of the Google Maps API is used if you don’t specify a version number? The latest release version perhaps? The documentation about versioning doesn’t say.

The documentation does recommend that production apps specify a minor version number. But it also says “all API changes will be backwards-compatible,” so is there any reason I should specify a version number if I’m not using any experimental features?

Answer 1

English is not my first language, so I might be reading this part wrong (from the versioning doc you linked)

You can indicate which version of the API to load within your application by specifying it using the v parameter … The nightly (development) version, specified with v=3 or by omitting the v parameter.

Further down, there’s a mention of 3.9 being nightly.

Documentation of Versions

Version 3.9 Reference (Nightly)

So, sounds like leaving out the v (which I do) will load the nightly, version 3.9.

<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>

About part two of your question: I can think of a very good reason to specify a version:

Consistency, predictability, reliability

You might want to keep the same look-and-feel while working on a update for the latest release of the Maps API. For example, the labels or map controls may move around.

On the other hand, it’s good to keep track of the latest versions, too. By lagging too far behind your application might stop working when it becomes unsupported.

I’m sure there are better reasons. I’m not a professional Maps developer.