Functions

These are the functions a Forms expression can call by name. A name that is not on this list is refused when you save. A function can also be written as helpers.len(...).

This list is written by hand against the evaluator’s list of built-in functions. Each example is run by tests/forms-docs-examples.php, so a function that changes behaviour fails the example.

Function	Gives
`len(x)`	The number of entries in a list, or characters in a text. 0 for `null`.
`sum(list)`	The total of the numbers in a list.
`avg(...)`, `min(...)`, `max(...)`	The average, lowest and highest of the numbers given, or of the numbers in a list.
`concat(...)`	The arguments joined as text, skipping blanks.
`join(list, separator)`	The entries of a list joined with a separator, skipping blanks.
`coalesce(...)`	The first argument that is not `null`.
`is_empty(x)`	True when there is no answer.
`match(value, /pattern/)`	True when the text matches the pattern.
`today()`, `now()`	Today’s date and the current time.
`format_date(date, format)`	A date as text.
`contains_text(text, phrase)`	True when the phrase is in the text, ignoring case and spacing.
`like_name(name, pattern)`	True when a file name fits a pattern with `*` and `?`.
`in_folder(path, folder)`	True when a path lies inside a folder.

Counting and totals

{"answers": {"tags": ["a", "b", "c"], "scores": [10, 20, 30], "v": [2, 4, 9]}}

len(answers.tags) > 2

true

sum(answers.scores)

avg(answers.v)

avg, min and max skip blank entries and text that is not a number. If nothing is left they give null.

{"answers": {"v": [10, "abc", 20], "empty": [null, ""]}}

avg(answers.v)

min(answers.v, 7)

max(answers.empty)

null

Joining text

concat and join skip null and "", so no stray separators appear when an optional question is blank.

{"answers": {"a": "Ada", "b": null, "c": "Lovelace", "v": ["a", null, "", "c"]}}

concat(answers.a, " ", answers.b, answers.c)

"Ada Lovelace"

join(answers.v, "-")

"a-c"

Defaults and blanks

{"answers": {"name": "Ada", "zero": 0}}

coalesce(answers.nickname, answers.name, "Anon")

"Ada"

is_empty(answers.zero)

false

Dates

today() and now() read the clock of the form. format_date(value, format) takes a date answer or text such as 2026-07-15. With no value it formats now. The format uses these letters: yyyy, yy, MMMM, MMM, MM, M, dd, d, EEEE, EEE, HH, H, hh, h, mm, ss, a. A value that is not a date gives null.

{"_now": "2026-05-30T12:00:00.000Z", "answers": {"dob": "1990-07-15"}}

today()

"2026-05-30"

format_date(answers.dob, "dd/MM/yyyy")

"15/07/1990"

today() and now() give text, not a date, so date methods do not work on them. For date arithmetic use mash.date.today(), or parse the date first. See Date methods.

{"_now": "2026-07-10T12:00:00.000Z"}

mash.date.today().subDays(90).toDateString()

"2026-04-11"

today().subDays(90)

error: Unknown method: subDays

Matching names and paths

These three are for forms that look at file names, such as a filing form.

{"answers": {"t": "I N V O I C E", "n": "DN_001.pdf", "p": "Notes/2026/a.pdf"}}

contains_text(answers.t, "invoice")

true

like_name(answers.n, "dn_*.PDF")

true

in_folder(answers.p, "notes")

true

in_folder matches whole folder names, so Notes does not hold Notes archive/a.pdf.

Calling a function that does not exist

nosuch(1)

error: Unknown function: nosuch