This Commented CUE demonstrates how to use the built-in function encoding/json.Compact to transform JSON held in a string into a single line of JSON with all insignificant whitespace removed.

file.cue
package example

import "encoding/json"

compact: json.Compact(jsonString)

// jsonString contains insignificant whitespace,
// split over several lines.
jsonString: #"""
	{
	  "a": 1,
	  "b": {
	    "c": "two",
	    "d": 3.0
	  },
	  "e": false,
	  "f": [
	    4,
	    5.0,
	    "A\nMulti\nLine\nString"
	  ]
	}
	"""#
TERMINAL
$ cue export -e compact --out text
{"a":1,"b":{"c":"two","d":3.0},"e":false,"f":[4,5.0,"A\nMulti\nLine\nString"]}