Posted 08 June 2017 - 04:51 PM
I realize it is not what you originally asked about and if not the most optimal choice if you have a laptop that does not have one built-in, but the other option would be a backlit keyboard. I find them rather handy when I want to work in the dark. Both of my laptops have them and I bought external keyboards with backlighting for both my Window desktops (one is wireless). The only keyboard that I currently use that is not backlight is the external keyboard I am using right now with my MacBook Pro (which I mostly use as a desktop replacement hooked to an external monitor, keyboard and mouse). This is largely because I cannot find a backlight keyboard for Mac (i.e. with Mac labeling on the keys). I can use one designed for Windows (i.e. with Windows labeling like a Windows key rather than a Command key) as all the keys will work, but I then need to remember how at least three of the key map from the Windows labels to what they do with the macOS.
The only downside is that usually backlight keyboards tend to cost more and will definitely cost more than a USB light. And of course, it will not be practical for use with a laptop except if you use the laptop as "desktop replacement" at a desk at home almost all the time. As soon as you want to use the laptops as, you know, a laptop (i.e. carry it around, use it on your lap, travel with it, etc), then it becomes impractical.