Having a variable as a JSON object key

Scenario:

You need to have a structure like this, where the variable is the key in the object, instead of the value. In this example, the string ”jonesa” needs to become a variable

{
  "userPerms": {
    "jonesa": "Editor"
  }
}

Solution:

The variable name can be enclosed in square brackets [ ] in the key field, creating a JSON structure like this:

{
  "userPerms": {
    [$username]: "Editor"
  }
}