Appendix B. Expression function reference

All functions, with examples evaluated against the guide's sample shipment (examples-data.json). Optional arguments are in [brackets]. In the designer, the Functions link under every expression box opens this page. Missing values are treated gracefully: text functions treat them as empty text, and number functions ignore them.

Lists and totals

Function	Returns
`count(list)`	The number of items
`sum(list, ['field'])`	The total of a field over the items (or of the items themselves)
`avg(list, ['field'])`	The average (0 for an empty list)
`min(list, ['field'])`, `max(list, ['field'])`	The smallest / largest value. Also `min(a, b, c…)` / `max(a, b, c…)`
`join(list, [separator])`	The items joined into text, separated by `,` unless you give a separator
`len(x)`	The length of a text or the number of items in a list

count(items)  →  3
sum(items, 'qty')  →  82
avg(items, 'qty')  →  27.333333333333332
min(items, 'qty')  →  10
max(items, 'qty')  →  48
max(3, 7, 5)  →  7
join(poNumbers, ' / ')  →  PO-780100 / PO-780137 / PO-780174
join(poNumbers)  →  PO-780100, PO-780137, PO-780174
len(poNumbers)  →  3
len(orderNumber)  →  9

The field argument can be a path into each item: sum(orders, 'totals.weight').

Numbers

Function	Returns
`round(n, [decimals])`	Rounded to the given decimals (default 0)
`floor(n)`, `ceil(n)`	Rounded down / up to a whole number
`abs(n)`	The value without its sign
`formatNumber(n, [decimals])`	Text with thousands separators in the document language. Without `decimals`, as many as needed
`formatCurrency(n, [code])`	Money in the document language. `code` is an ISO currency code (default `USD`)

round(totalWeight)  →  2942
round(totalWeight, 1)  →  2942.5
floor(9.99)  →  9
ceil(9.01)  →  10
abs(-5)  →  5
formatNumber(totalWeight)  →  2,942.456
formatNumber(totalWeight, 2)  →  2,942.46
formatCurrency(declaredValue)  →  $1,250.00
formatCurrency(declaredValue, 'EUR')  →  €1,250.00
# locale: fr-FR
formatCurrency(declaredValue, 'EUR')  →  1 250,00 €

Text

Function	Returns
`upper(s)`, `lower(s)`	UPPERCASE / lowercase
`trim(s)`	Without leading and trailing spaces
`concat(a, b, …)`	All arguments joined together
`substr(s, start, [length])`	Part of the text, from position `start` (0 = first character)
`replace(s, find, with)`	Every occurrence of `find` replaced
`pad(s, length, [char])`	Padded on the left to `length` with `char` (default space). Maximum length 10,000
`truncate(s, length)`	Cut to `length` characters, ending in `…` when shortened
`json(x)`	The value written as JSON text (useful for QR codes)

upper(shipTo.city)  →  COLUMBUS
lower('PREPAID')  →  prepaid
trim('  A-02-A-01  ')  →  A-02-A-01
concat(shipTo.city, ', ', shipTo.state)  →  Columbus, OH
substr(orderNumber, 3)  →  104412
substr(sscc, 1, 7)  →  0614141
replace(orderNumber, '-', '')  →  SO104412
pad(carrier.proNumber, 10, '0')  →  0078121007
pad('7', 3)  →  "  7"
truncate(items[1].description, 15)  →  Power bank 20,…
json(carrier)  →  {"name":"Southeastern Freight Lines","scac":"SEFL","proNumber":"78121007"}

Dates

Function	Returns
`formatDate(d, [pattern])`	The date as text (default pattern `MM/DD/YYYY`). See the token table in chapter 6
`today()`	The current date and time (same as `now`)

formatDate(orderDate)  →  10/18/2026
formatDate(shipDate, 'ddd, MMM D YYYY h:mm A')  →  Tue, Oct 20 2026 3:45 PM
formatDate(today(), 'YYYY-MM-DD')  →  2026-10-20
formatDate(now, 'YYMMDD')  →  261020

Logic

Function	Returns
`if(condition, a, b)`	`a` if the condition is true, otherwise `b` (same as `condition ? a : b`)
`coalesce(a, b, …)`	The first argument that isn't missing or empty text

if(hazmat, 'HAZMAT', 'NON-HAZMAT')  →  HAZMAT
if(cartons > 1, 'cartons', 'carton')  →  cartons
coalesce(notes, shipTo.attention, 'None')  →  None
coalesce(customer.code, customer.name)  →  NW-55021

Operators (summary)

Kind	Operators
Arithmetic	`+` `-` `*` `/` `%` (and `+` joins text)
Comparison	`==` `!=` `===` `!==` `<` `<=` `>` `>=`
Logic	`&&` (and), `\|\|` (or), `!` (not), `??` (default for missing), `a ? b : c`
Grouping and literals	`( )`, `'text'` / `"text"`, `123`, `1.5`, `true`, `false`, `null`, `[a, b]`

Limits

To keep rendering fast and safe, an expression's text result may be at most 1,000,000 characters, pad at most 10,000, and expressions at most 10,000 characters long and nested at most 100 levels deep. A result over a limit prints empty and produces a warning.