Loading...
Loading...
if/for/while, arrow functions) plus a specific set of builtin functions and the $(...) variable-reference syntax. This page is a lookup reference for what's actually supported. For the v1.8 syntax changes if you're upgrading an existing system, see Update expressions for v1.8. Kind | Operators |
|---|
Arithmetic / bitwise | `+ - * / % ^ ** >> << & \ | (^ is bitwise XOR here, not exponent: use `** for exponent) |
Comparison | == != === !== > < >= <= |
Logical | `\ | \ | && ??` (nullish coalescing) |
Unary | - + ! ~ |
Update | ++ -- (prefix or postfix) |
Assignment | `= *= **= /= %= += -= <<= >>= &= ^= \ | = \ | \ | = &&= ??=` |
Other | Ternary ( a ? b : c), comma/sequence (a, b, c), spread (...arr), grouping |
+ behaves like JavaScript's numeric addition first: it only falls back to string concatenation when the numeric result would be NaN, so '1' + '2' gives 3, but 'a' + 1 gives 'a1'.if/else, while, for, for...of (unlabelled break/continue only), return, let/const (not var), and simple arrow functions ((x) => x + 1: no destructured parameters, not async).await, yield, this, tagged template literals, regex literals, BigInt literals, getters/setters, destructuring, optional calls (fn?.()), and method-style calls on a value (a.b()): only direct function calls are supported.{...} at the very start of an expression is read as an object literal, not a code block: for example, { 1: 'on', 2: 'off' }[$(internal:state)] is valid and works as a lookup table. Function | What it does |
|---|---|
round(v) / floor(v) / ceil(v) / abs(v) | Standard rounding |
sqrt(v) / pow(base, exponent) | Square root, exponentiation |
log(v, base?) / log10(v) / exp(v) | Logarithm (natural, or given base) and exponential |
max(...) / min(...) | Largest/smallest of the given values |
randomInt(min=0, max=10) | Random inclusive integer |
fromRadix(str, radix=10) / toRadix(v, radix=10) | Convert between a number and a string in a given base (2–36) |
toFixed(v, dp=0) | Fixed decimal places (0–100) |
isNumber(v) | True for a number, bigint, or a non-blank numeric string |
Function | What it does |
|---|---|
length(v) | Length of a string (counting whole characters, not UTF-16 units), array, number, or object (key count) |
strlen(v) | Raw string length in UTF-16 code units |
trim(v) | Trims whitespace |
substr(str, start, end) / split(str, sep?) / join(arr, sep=',') | Slice, split, and join |
concat(...) | Concatenates strings |
includes(str, sub) / indexOf(str, sub, offset?) / lastIndexOf(str, sub, offset?) | Search within a string |
toUpperCase(str) / toLowerCase(str) / replaceAll(str, find, replace) | Case and replacement |
stringCompare(a, b) | Locale-aware comparison, for use in a sort callback |
encode(str, enc) / decode(str, enc) | Encode/decode using a Buffer encoding (default latin1) |
encodeURI(str) / decodeURI(str) / encodeURIComponent(str) / decodeURIComponent(str) | Standard URI encoding |
Function | What it does |
|---|---|
bool(v) | Truthy, except the strings 'false' and '0' (case-insensitive) are false |
Function | What it does |
|---|---|
jsonpath(obj, path) | JSONPath query: auto-parses a JSON string input |
jsonparse(str) / jsonstringify(obj) | Parse/stringify JSON, returning null on failure |
objectKeys(obj) / objectValues(obj) | Like their JavaScript equivalents |
arrayIncludes / arrayIndexOf / arrayLastIndexOf | Search within an array |
arrayMap / arrayFilter / arrayFind / arrayFindIndex / arraySome / arrayEvery / arrayForEach | Standard iteration, each taking a callback function |
arrayReduce(arr, fn, initial) | Reduce with an (accumulator, value, index) callback |
arraySort(arr, fn?) / arrayReverse(arr) / arraySlice(arr, start, end) | Return a new, modified copy: the original array is untouched |
arrayConcat(...) / arrayFlat(arr) | Combine arrays, or flatten one level |
"{name}() requires a function as its callback argument" if you pass something that isn't one: a common mistake worth checking first if one of these errors unexpectedly. Function | What it does |
|---|---|
unixNow() | Current time in milliseconds |
parseDate(v) | Parses a date-like value to unix milliseconds, or null |
dateYear / dateMonth / dateDay / dateHour / dateMinute / dateSecond / dateWeekday (v, tz?) | Individual date parts (weekday: 0 = Sunday) |
dateFormat(v, fmt='YYYY-MM-DDTHH:mm:ss', tz?) | Formats using tokens like YYYY MM DD HH mm ss, or 'ISO' |
dateAdd(v, amount, unit) | Adds a calendar amount ( unit = second/minute/hour/day/week/month/year), DST-safe |
timestampToSeconds(str) / secondsToTimestamp(v, format?) / msToTimestamp(v, format?) | Convert between a HH:MM:SS-style timestamp and a numeric duration |
timeOffset(time, offset, hr12?) | Adds an offset to a time-of-day string |
timeDiff(from, to) | Seconds between two times |
Function | What it does |
|---|---|
getVariable(name) / getVariable(label, name) | Reads a variable's current value dynamically: this is the only supported way to look up a variable by a computed name; the older getVariableValue alias was removed in v1.8 |
parseVariables(str, undefinedValue?) | Substitutes every $(...) reference found inside a string and returns the resolved result: this is also how you get inside-out nested-reference resolution inside an expression, since $(...) itself doesn't nest as a literal token (see Understand nested variables) |
Function | What it does |
|---|---|
blink(interval, dutyCycle=0.5) | Returns 1/0, toggling on a repeating interval (minimum 100ms) |
oscillate(period, waveform='sine', phase=0) | Returns a continuous 0–1 value cycling over a period; waveform is sine, triangle, sawtooth, or square |
Note
blink, oscillate, and parseVariables only work where Buttons can supply a live clock/variable context: on a button, feedback, or similar continuously-evaluated field. They throw "{name} is not supported here" inside a Workflow Expression node, which evaluates once and has no ongoing context to re-run against.
PI is available as a bare identifier (Math.PI), not a function call.$(...) variable reference#$(...), use letters, digits, _, -, :, and . to identify a variable: Buttons reads this as a dot-joined path (for example ns.a). The reference is read as one opaque token up to its first ); it does not parse a literal nested $(...) inside it. See Understand nested variables for the two mechanisms that do support nesting in practice. Message | What it means |
|---|---|
Unsupported function "{name}" | The function name doesn't exist: check spelling, and remember getVariableValue was removed in v1.8 (use getVariable). |
{name}() requires a function as its callback argument | An array function like arrayMap was called without a real callback function. |
{name} is not supported here | You called blink, oscillate, or parseVariables somewhere without a live clock/variable context, such as a Workflow Expression node. |
Unsupported syntax "{type}" / Unsupported binary/logical/assignment operator "{op}" | The expression uses a construct or operator that isn't on the supported list. |
Only direct function calls are supported | You tried to call a method on a value ( a.b()) rather than calling a plain function. |
Access to property "{property}" is not allowed | The expression touched a banned property name ( __proto__, constructor, prototype, and similar). |
Expression evaluation exceeded the maximum number of operations / ...maximum call depth | The expression is too large or recurses too deeply to safely evaluate: simplify it. |
What you see | What to try |
|---|---|
A function you expect to exist throws "Unsupported function." | Double check the exact name against this page: a similar-sounding function elsewhere in JavaScript may not exist here. |
blink/oscillate/parseVariables throws "not supported here." | You're likely inside a Workflow Expression node: these only work in continuously-evaluated contexts like a button or feedback. |
A $(something_$(something_else))-style nested reference doesn't resolve as expected inside an expression. | Use parseVariables(...) instead: the $(...) token itself doesn't parse a literal nested reference. |
An array function throws about needing a callback. | Confirm you're actually passing a function, not a value, as that argument. |
Was this helpful?
0 of 0 users found this page helpful