Functions

Functions work in conditions and values: if count($tabs) > 3, set n = round($x, 2). The time, browser and page functions work in Roost Script too, under the names in the last column; for the rest, Roost Script uses JavaScript's own methods (list.length, text.toLowerCase(), Math.round()).

Lists and text

Roost Basic	Does	Roost Script
`count()`	how many items (or letters)	JavaScript’s own
`len()`	same as count	JavaScript’s own
`empty()`	true if there’s nothing	JavaScript’s own
`first()`	the first item	JavaScript’s own
`last()`	the last item	JavaScript’s own
`join()`	a list as text: join($tabs, " / ")	JavaScript’s own
`split()`	text into a list	JavaScript’s own
`contains()`	contains(text or list, "words")	JavaScript’s own
`startswith()`	startswith(text, "start")	JavaScript’s own
`endswith()`	endswith(text, "end")	JavaScript’s own
`lower()`	lowercase text	JavaScript’s own
`upper()`	uppercase text	JavaScript’s own
`trim()`	text without spaces around it	JavaScript’s own
`replace()`	replace(text, "old", "new")	JavaScript’s own
`text()`	anything as text	JavaScript’s own
`number()`	the first number in some text	JavaScript’s own

Numbers

Roost Basic	Does	Roost Script
`round()`	round(3.14159, 2)	`Math.roundTo()`
`floor()`	round down	`Math.floor()`
`ceil()`	round up	`Math.ceil()`
`abs()`	abs(-3) is 3	`Math.abs()`
`sqrt()`	square root	`Math.sqrt()`
`pow()`	pow(2, 10) is 1024	`Math.pow()`
`min()`	the smallest number	`Math.min()`
`max()`	the largest number	`Math.max()`
`sum()`	sum($prices): all the numbers added up	`Math.sum()`
`avg()`	the average	`Math.avg()`
`median()`	the middle number	`Math.median()`
`stdev()`	how spread out the numbers are (standard deviation)	`Math.stdev()`
`clamp()`	clamp(x, 1, 10): x, kept between 1 and 10	`Math.clamp()`
`percent()`	percent(3, 12) is 25	`Math.percent()`
`format()`	format(1234.5) is "1,234.50"; format(x, 0) for no decimals	`Math.format()`
`gcd()`	greatest common divisor	`Math.gcd()`
`lcm()`	least common multiple	`Math.lcm()`
`isprime()`	whether a whole number is prime	`Math.isPrime()`
`random()`	random(1, 6): a whole number between them	`Math.randomInt()`
`range()`	range(1, 5): 1, 2, 3, 4, 5	JavaScript’s own

Hashes

Checksums as hex text, for checking text against a published checksum or noticing when something changed. md5 and sha1 are fine for that, not for secrets. The hash command does the same for piped lines: page --css "#terms" | hash.

Roost Basic	Does	Roost Script
`md5()`	md5 hash (hex) of some text	`md5()`
`sha1()`	sha1 hash (hex)	`sha1()`
`sha256()`	sha256 hash (hex)	`sha256()`
`sha512()`	sha512 hash (hex)	`sha512()`
`hash()`	hash(text, "sha384"): md5, sha1, sha256, sha384 or sha512	`hash()`

Time

Roost Basic	Does	Roost Script
`hour()`	the hour now (0–23)	`hour()`
`minute()`	the minute now	`minute()`
`weekday()`	monday … sunday	`weekday()`
`today()`	the date, like 2026-11-11	`today()`
`now()`	the time, like 09:30	`now()`

The browser

Roost Basic	Does	Roost Script
`title()`	the title of the tab you’re on	`title()`
`url()`	the address of the tab you’re on	`url()`
`tabcount()`	how many tabs are open	`tabCount()`
`site()`	the site of an address or tab	`site()`

Page checks

These read the tab you're on, so a script can look before it acts: if exists("Accept all"). They see what's on the screen, and only text: they can't change the page.

Roost Basic	Does	Roost Script
`has()`	whether the page shows some text: has("Sold out")	`has()`
`exists()`	whether there’s a button or link with that text: exists("Next page")	`exists()`
`read()`	the text of the first thing matching a CSS selector: read("h1")	`read()`
`readall()`	the text of everything matching a CSS selector, as a list: readall(".price")	`readAll()`
`value()`	what a field on the page holds: value("Email")	`value()`

Roost Basic

if has("Sold out")
  notify "Still sold out"
else if exists("Add to cart")
  click "Add to cart"
end
set prices = readall(".price")
print "First price: $(first($prices))"