split(", ")
"a, b,c,d, e, "
["a","b,c,d","e",""]

walk( if type == "object" then with_entries( .key |= sub( "^_+"; "") ) else . end )
[ { "_a": { "__b": 2 } } ]
[{"a":{"b":2}}]

test("foo")
"foo"
true

.[] | test("a b c # spaces are ignored"; "ix")
["xabcd", "ABC"]
true
true

match("(abc)+"; "g")
"abc abc"
{"offset": 0, "length": 3, "string": "abc", "captures": [{"offset": 0, "length": 3, "string": "abc", "name": null}]}
{"offset": 4, "length": 3, "string": "abc", "captures": [{"offset": 4, "length": 3, "string": "abc", "name": null}]}

match("foo")
"foo bar foo"
{"offset": 0, "length": 3, "string": "foo", "captures": []}

match(["foo", "ig"])
"foo bar FOO"
{"offset": 0, "length": 3, "string": "foo", "captures": []}
{"offset": 8, "length": 3, "string": "FOO", "captures": []}

match("foo (?<bar123>bar)? foo"; "ig")
"foo bar foo foo  foo"
{"offset": 0, "length": 11, "string": "foo bar foo", "captures": [{"offset": 4, "length": 3, "string": "bar", "name": "bar123"}]}
{"offset": 12, "length": 8, "string": "foo  foo", "captures": [{"offset": -1, "length": 0, "string": null, "name": "bar123"}]}

[ match("."; "g")] | length
"abc"
3

capture("(?<a>[a-z]+)-(?<n>[0-9]+)")
"xyzzy-14"
{ "a": "xyzzy", "n": "14" }

scan("c")
"abcdefabc"
"c"
"c"

split(", *"; null)
"ab,cd, ef"
["ab","cd","ef"]

splits(", *")
"ab,cd,   ef, gh"
"ab"
"cd"
"ef"
"gh"

sub("[^a-z]*(?<x>[a-z]+)"; "Z\(.x)"; "g")
"123abc456def"
"ZabcZdef"

[sub("(?<a>.)"; "\(.a|ascii_upcase)", "\(.a|ascii_downcase)")]
"aB"
["AB","aB"]

gsub("(?<x>.)[^a]*"; "+\(.x)-")
"Abcabc"
"+A-+a-"

[gsub("p"; "a", "b")]
"p"
["a","b"]