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Functions over strings. Positions and lengths count UTF-16 code units, as in JavaScript. includes, indexOf, replace, and replaceAll match literal text; matches tests a regular expression.

Every function can be called as f(x, ...) or as a method, x.f(...). In the signatures, T and U stand for any type, T[] is a list, ? marks an optional parameter, and (T, number) => boolean is a lambda parameter.

Function	Description
toUpperCase	Upper-cases text.
toLowerCase	Lower-cases text.
trim	Removes leading and trailing whitespace.
trimStart	Removes leading whitespace.
trimEnd	Removes trailing whitespace.
startsWith	Whether text starts with a prefix.
endsWith	Whether text ends with a suffix.
includes	Whether text contains a substring, or a list contains a value.
indexOf	Position of the first match, or -1.
lastIndexOf	Position of the last match, or -1.
slice	A section of text or a list; negative positions count from the end.
split	Splits text on a separator.
replace	Replaces the first occurrence of some text (no patterns).
replaceAll	Replaces every occurrence of some text (no patterns).
padStart	Pads text at the start to a length.
padEnd	Pads text at the end to a length.
repeat	Repeats text a number of times.
at	The item or character at a position; negative positions count from the end.
matches	Whether text contains a match for a regular expression (JavaScript syntax without backreferences or lookaround, linear time; anchor with ^ and $; prefix (?i) to ignore case).
toString	Renders a value as text, as a template would.
toNumber	Parses decimal text as a number, e.g. "-12.5" or "1e3" (surrounding whitespace is ignored; 0x and other bases are not accepted).

toUpperCase

Upper-cases text.

• toUpperCase(string): string

"hello".toUpperCase() // => "HELLO"

toLowerCase

Lower-cases text.

• toLowerCase(string): string

toLowerCase("Hello") // => "hello"

trim

Removes leading and trailing whitespace.

• trim(string): string

"  hi  ".trim() // => "hi"

trimStart

Removes leading whitespace.

• trimStart(string): string

"  hi  ".trimStart() // => "hi  "

trimEnd

Removes trailing whitespace.

• trimEnd(string): string

"  hi  ".trimEnd() // => "  hi"

startsWith

Whether text starts with a prefix.

• startsWith(string, string): boolean

"invoice-42".startsWith("invoice-") // => true

endsWith

Whether text ends with a suffix.

• endsWith(string, string): boolean

"report.pdf".endsWith(".pdf") // => true

includes

Whether text contains a substring, or a list contains a value.

• includes(string, string): boolean

"hello world".includes("lo w") // => true

indexOf

Position of the first match, or -1.

• indexOf(string, string): number

"banana".indexOf("an") // => 1
"banana".indexOf("x") // => -1

lastIndexOf

Position of the last match, or -1.

• lastIndexOf(string, string): number

"banana".lastIndexOf("an") // => 3

slice

A section of text or a list; negative positions count from the end.

• slice(string, number, number?): string

"hello".slice(1, 3) // => "el"
"hello".slice(-3) // => "llo"

split

Splits text on a separator.

• split(string, string, number?): string[]

"a,b,c".split(",") // => ["a", "b", "c"]
"a,b,c".split(",", 2) // => ["a", "b"]

replace

Replaces the first occurrence of some text (no patterns).

• replace(string, string, string): string

"a-b-c".replace("-", "+") // => "a+b-c"

replaceAll

Replaces every occurrence of some text (no patterns).

• replaceAll(string, string, string): string

"a-b-c".replaceAll("-", "+") // => "a+b+c"

padStart

Pads text at the start to a length.

• padStart(string, number, string?): string

"7".padStart(3, "0") // => "007"

padEnd

Pads text at the end to a length.

• padEnd(string, number, string?): string

"ab".padEnd(4, ".") // => "ab.."

repeat

Repeats text a number of times.

• repeat(string, number): string

"ab".repeat(3) // => "ababab"

at

The item or character at a position; negative positions count from the end.

• at(string, number): string | null

"hello".at(-1) // => "o"
"hello".at(10) // => null

matches

Whether text contains a match for a regular expression (JavaScript syntax without backreferences or lookaround, linear time; anchor with ^ and $; prefix (?i) to ignore case).

• matches(string, string): boolean

"INV-2041".matches("^INV-[0-9]+$") // => true
"Hello".matches("(?i)^hello$") // => true
"a.b".matches("a\\.b") // => true

toString

Renders a value as text, as a template would.

• toString(string | number | boolean | null | timestamp | duration): string

toString(42) // => "42"
toString(null) // => ""
days(1).toString() // => "P1D"

toNumber

Parses decimal text as a number, e.g. "-12.5" or "1e3" (surrounding whitespace is ignored; 0x and other bases are not accepted).

• toNumber(string | number): number

"42.5".toNumber() // => 42.5
" -1e3 ".toNumber() // => -1000
try("0x10".toNumber(), 0) // => 0