Peter Lyons

Dec 10, 2016

JSON comment tricks

So as you have probably learnt and been frustrated by, JSON does not officially support comments. This, as I understand it, was done intentionally by JSON's creator Douglas Crockford to prevent abuse of comments for non-standard metadata. Be that as it may, and it may make sense for a data interchange format, JSON is used for configuration files commonly and the lack of comments can be frustrating. Here's some hacky tricks I sometimes use.

Disable keys with a prefix

Let's say I need to quickly switch a config file between a version with and without a certain value:

{"proxy": "http://proxy.example.com:8765"}

To disable it, I "comment it out" by changing the name of the property.

{"OFFproxy": "http://proxy.example.com:8765"}

Usually this has the desired effect and no ill side effects. I can imagine there are strict cases where it won't work, but mostly it's effective.

Add comments above

Here's how I add "comments"

{
  "// Use this when in the Narnia office": 0,
  "OFFproxy": "http://proxy-na.example.com:8765",
  "// Use this when in the Whoville office": 0,
  "proxy": "http://proxy-wv.example.com:8765"
}

I just start a key with "//" and set the value to zero. Usually works OK.