$ fq -i -n '"[]" | json'
json> (.) | ., tovalue, type, length?
   |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
0x0|5b 5d|                                         |[]|             |.: [0:0] (json)
[]
"array"
0
json> (.)[0] | ., type, length?
null
"null"
0
json> (.)[-1000] | ., type, length?
null
"null"
0
json> (.)[1000] | ., type, length?
null
"null"
0
json> (.)[1:3] | ., type, length?
[]
"array"
0
json> (.)[0:-1] | ., type, length?
[]
"array"
0
json> (.)[-1000:2000] | ., type, length?
[]
"array"
0
json> (.)["test"] | ., type, length?
error: expected an object but got: array
json> [(.)[]] | type, length?
"array"
0
json> (.) | keys
[]
json> (.) | has("a")
error: cannot check whether array has a key: a
json> (.) | has(0)
false
json> (.) | type
"array"
json> (.) | tonumber
error: tonumber cannot be applied to: array
json> (.) | tostring
error: tostring cannot be applied to: array
json> (.) + ""
error: cannot add: array ([]) and string ("")
json> (.) + 1
error: cannot add: array ([]) and number (1)
json> (.)._start | ., type, length?
0
"number"
0
json> (.)._stop | ., type, length?
16
"number"
16
json> (.)._len | ., type, length?
16
"number"
16
json> (.)._name | ., type, length?
""
"string"
0
json> (.)._sym | ., type, length?
null
"null"
0
json> (.)._description | ., type, length?
null
"null"
0
json> (.)._path | ., type, length?
[]
"array"
0
json> (.)._bits | ., type, length?
   |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
0x0|5b 5d|                                         |[]|             |.: raw bits 0x0-0x1.7 (2)
"binary"
16
json> 
json> (.)._bytes | ., type, length?
   |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
0x0|5b 5d|                                         |[]|             |.: raw bits 0x0-0x1.7 (2)
"binary"
2
json> 
json> (.)._error | ., type, length?
null
"null"
0
json> (.)._unknown | ., type, length?
false
"boolean"
json> (.).a = 1
error: expected an object but got: array
json> (.)[0] = 1
[
  1
]
json> (.).a |= empty
error: expected an object but got: array
json> (.)[0] |= empty
[]
json> (.) | setpath(["a"]; 1)
error: expected an object but got: array ([])
json> (.) | setpath([0]; 1)
[
  1
]
json> (.) | delpaths([["a"]])
error: expected an object but got: array ([])
json> (.) | delpaths([[0]])
[]
json> ^D