JS Stdlib

Use this page when you need a quick answer to "does Targo support the JS-flavored API I am reaching for here?"

The key question is not only whether something is supported, but also whether it behaves:

• close to the familiar JS surface
• with Go-shaped return values or control flow
• through runtime-backed Targo types rather than native Go containers

When this page and older notes disagree, trust the current runtime declarations and doc fixtures.

For collection types (Array<T>, Map<K, V>, Set<T>, slice<T>, map<K, V>), see collections.md.

JSON and Object Helpers

API	Status	Notes
JSON.stringify(value)	Supported with Go-shaped errors	Returns [string, error | null], not a thrown exception
JSON.parse<T>(text)	Supported with Go-shaped errors	Returns [T, error | null], not a thrown exception
Object.keys(obj)	Supported	Runtime helper; returns slice<string>
Object.values(obj)	Supported	Runtime helper; returns slice<unknown>
Object.entries(obj)	Not currently documented in the runtime surface	Do not assume it exists until the declarations expose it

If you are serializing or parsing at a package boundary, treat JSON as part of Targo's Go-style error model, not JavaScript exception flow.

Console, Math, and Numeric Globals

API	Status	Notes
console.log(...)	Supported	Maps directly to Go fmt.Println(...)
console.error(...)	Supported	Maps to fmt.Fprintln(os.Stderr, ...)
NaN / Infinity	Supported	Exposed as globals mapped to Go math helpers
isNaN(x) / isFinite(x)	Supported	Go-backed numeric helpers
Math.*	Broadly supported	Constants and common helpers such as floor, ceil, round, pow, sqrt, log, sin, atan2, min, and max

Important caveat:

• Math operates on float64-shaped values. Do not assume JavaScript's single number mental model is always the right API shape inside Targo code.

Strings and RegExp

API	Status	Notes
Common string methods	Broadly supported	trim, trimStart, trimEnd, toUpperCase, toLowerCase, includes, startsWith, endsWith, indexOf, lastIndexOf, split, replace, replaceAll, repeat, padStart, padEnd, slice, substring, charAt, charCodeAt, and at
str.length	Supported with Go-shaped semantics	Follows Go len, so re-check Unicode assumptions
RegExp literals and constructor	Supported	Backed by Go's RE2 engine
RegExp.test() / RegExp.exec()	Supported	exec() returns Array<string> | null
string.match() / matchAll() / search() / replace() / split() with RegExp	Supported	Runtime declarations provide RegExp overloads

Important caveats:

• RegExp behavior follows RE2 constraints. Do not assume lookahead, lookbehind, or backreferences are available.
• String length and search positions follow Go-oriented indexing rules. Re-check byte-versus-character assumptions when correctness depends on Unicode details.

Unsupported or Risky JS Runtime Assumptions

API	Status	Notes
Promise	Not supported	No JS promise runtime
async/await	Not supported	Use Go concurrency primitives
setTimeout / setInterval	Not supported as JS timers	Use Go time APIs instead
fetch	Not supported as a JS global	Use Go packages such as net/http
DOM / browser globals	Not supported by default	Only rely on them if the target environment explicitly provides them

Practical Rules

• If the API belongs to JS async runtime behavior, assume it is unavailable until the current declarations prove otherwise.
• If the API looks JS-familiar but returns [T, error | null], treat it as a Go-shaped boundary, not a JS convenience wrapper.
• If behavior depends on string length, indexing, or regex edge cases, verify against current runtime declarations and fixtures rather than guessing from JavaScript habits.