Type Methods and Properties

June 26, 2026 · View on GitHub

Status of built-in methods and properties on GiavaScript runtime types.

String

Member	Kind	Status
`length`	Instance property	Available
`at()`	Instance method	Available
`charAt()`	Instance method	Available
`charCodeAt()`	Instance method	Available
`codePointAt()`	Instance method	Available
`concat()`	Instance method	Available
`endsWith()`	Instance method	Available
`fromCharCode()`	Static method	Available
`includes()`	Instance method	Available
`indexOf()`	Instance method	Available
`isWellFormed()`	Instance method	Available
`lastIndexOf()`	Instance method	Available
`localeCompare()`	Instance method	Available
`match()`	Instance method	Available
`matchAll()`	Instance method	Available
`padEnd()`	Instance method	Available
`padStart()`	Instance method	Available
`repeat()`	Instance method	Available
`replace()`	Instance method	Available
`replaceAll()`	Instance method	Available
`search()`	Instance method	Available
`slice()`	Instance method	Available
`split()`	Instance method	Available
`startsWith()`	Instance method	Available
`substr()`	Instance method	Not available
`substring()`	Instance method	Available
`toLocaleLowerCase()`	Instance method	Available
`toLocaleUpperCase()`	Instance method	Available
`toLowerCase()`	Instance method	Available
`toString()`	Instance method	Available
`toUpperCase()`	Instance method	Available
`toWellFormed()`	Instance method	Available
`trim()`	Instance method	Available
`trimEnd()`	Instance method	Available
`trimStart()`	Instance method	Available
`valueOf()`	Instance method	Available

Number

Member	Kind	Status
`isFinite()`	Static method	Available
`isInteger()`	Static method	Available
`isNaN()`	Static method	Available
`toString()`	Instance method	Available

Array

Member	Kind	Status
`from()`	Static method	Available
`fromAsync()`	Static method	Not available
`isArray()`	Static method	Available
`of()`	Static method	Available
`length`	Instance property	Available
`at()`	Instance method	Available
`concat()`	Instance method	Available
`copyWithin()`	Instance method	Available
`entries()`	Instance method	Available
`every()`	Instance method	Available
`fill()`	Instance method	Available
`filter()`	Instance method	Available
`find()`	Instance method	Available
`findIndex()`	Instance method	Available
`findLast()`	Instance method	Available
`findLastIndex()`	Instance method	Available
`flat()`	Instance method	Available
`flatMap()`	Instance method	Available
`forEach()`	Instance method	Available
`includes()`	Instance method	Available
`indexOf()`	Instance method	Available
`join()`	Instance method	Available
`keys()`	Instance method	Available
`lastIndexOf()`	Instance method	Available
`map()`	Instance method	Available
`pop()`	Instance method	Available
`push()`	Instance method	Available
`reduce()`	Instance method	Available
`reduceRight()`	Instance method	Available
`reverse()`	Instance method	Available
`shift()`	Instance method	Available
`slice()`	Instance method	Available
`some()`	Instance method	Available
`sort()`	Instance method	Available
`splice()`	Instance method	Available
`toLocaleString()`	Instance method	Not available
`toReversed()`	Instance method	Not available
`toSorted()`	Instance method	Not available
`toSpliced()`	Instance method	Not available
`toString()`	Instance method	Available
`unshift()`	Instance method	Available
`values()`	Instance method	Available
`with()`	Instance method	Not available

Array callback argument behavior

In array methods that accept callbacks, JavaScript-compatible argument normalization applies to user-defined function expressions and references to function declarations.
Extra callback arguments are ignored.
Missing callback arguments are passed as undefined.

Object

Member	Kind	Status
`assign()`	Static method	Available
`entries()`	Static method	Available
`hasOwn()`	Static method	Available
`keys()`	Static method	Available
`toString()`	Instance method	Available
`values()`	Static method	Available

Boolean

Member	Kind	Status
`toString()`	Instance method	Available

Date

Member	Kind	Status
`getTime()`	Instance method	Available
`toString()`	Instance method	Available

Date notes

In Node.js, Date.prototype.toString() usually prints a locale/timezone representation.
In GiavaScript, Date.prototype.toString() returns a UTC ISO-like string (YYYY-MM-DDTHH:mm:ss.SSSZ) by design.

Error

Member	Kind	Status
`Error()`	Constructor	Available
`message`	Instance property	Available
`name`	Instance property	Available
`stack`	Instance property	Available
`toString()`	Instance method	Available
`TypeError()`	Constructor	Available
`ReferenceError()`	Constructor	Available
`SyntaxError()`	Constructor	Available

Error notes

new Error("message") creates an error object with the given message.
name defaults to "Error". Subtypes use their constructor name.
stack returns a string representation of the call stack.
toString() returns "name: message".
Error objects can be thrown with throw and caught with try/catch.
Raw value throws continue to work alongside Error objects.

Notes

This reflects the current behavior in the interpreter and specs.