Runtime reference

Timers

Global timer functions, behaving like their browser counterparts.

F setTimeout

setTimeout(callback: (...args: any[]) => void, delay: number, ...args: any[]): number

Runs callback once after delay ms. Returns a timer ID.

F clearTimeout

clearTimeout(id: number): void

Cancels a pending timeout. Safe to call with an invalid ID.

F setInterval

setInterval(callback: (...args: any[]) => void, period: number, ...args: any[]): number

Runs callback repeatedly every period ms. Returns a timer ID.

F clearInterval

clearInterval(id: number): void

Cancels a repeating interval.

F queueMicrotask

queueMicrotask(callback: () => void): void

Queues callback as a microtask, before the next timer/IO callback.

---

O console

All output is forwarded to the daemon event stream and, if a PTY is attached, written directly to it. Arguments are space-joined. No %s / %d printf-style substitution.

F console.log

log(...args: any[]): void

Logs at INFO level.

F console.info

info(...args: any[]): void

Logs at INFO level.

F console.warn

warn(...args: any[]): void

Logs at WARN level.

F console.error

error(...args: any[]): void

Logs at ERROR level.

F console.debug

debug(...args: any[]): void

Logs at DEBUG level.

F console.assert

assert(condition: boolean, ...args: any[]): void

Logs at ERROR level if condition is falsy. No-op otherwise.

F console.clear

clear(): void

Sends ANSI clear-screen.

F console.count

count(label?: string): void

Increments and prints a named counter.

F console.countReset

countReset(label?: string): void

Resets the named counter.

F console.dir

dir(obj: any): void

Pretty-prints an object.

F console.group

group(...args: any[]): void

Logs and increases the indent level.

F console.groupEnd

groupEnd(): void

Decreases the indent level.

F console.table

table(data: any[] | Record<string, any>): void

Formats an array or object as an ASCII table.

F console.time

time(label?: string): void

Starts a named timer.

F console.timeLog

timeLog(label?: string): void

Logs elapsed time without stopping the timer.

F console.timeEnd

timeEnd(label?: string): void

Logs elapsed time and stops the timer.

F console.trace

trace(...args: any[]): void

Logs "Trace: ..." with optional args.

---

Text encoding

The web's TextEncoder and TextDecoder, following the Encoding Standard. Both are globals in every isolate, workers included.

O TextEncoder

class TextEncoder {
  readonly encoding: "utf-8";
  encode(input?: string): Uint8Array;
  encodeInto(source: string, destination: Uint8Array): { read: number; written: number };
}

Encodes strings as UTF-8, the only encoding the standard encodes to. encodeInto writes as much of source as fits without splitting a character. read counts UTF-16 code units, written counts bytes. For UTF-16 or UTF-32 code units, use toUTF16 / toUTF32 from yeet:tui:text.

O TextDecoder

class TextDecoder {
  constructor(label?: string, options?: { fatal?: boolean; ignoreBOM?: boolean });
  readonly encoding: string;
  readonly fatal: boolean;
  readonly ignoreBOM: boolean;
  decode(input?: ArrayBuffer | ArrayBufferView, options?: { stream?: boolean }): string;
}

Decodes bytes in any encoding the standard names. label is any of its labels ("utf-8", "utf-16le", "utf-16be", "windows-1252", "shift_jis", …), and encoding is the canonical name it resolves to. An unknown label throws RangeError. With fatal, malformed input throws TypeError instead of decoding to U+FFFD. With ignoreBOM, a leading byte order mark stays in the output. With { stream: true }, a character split across calls carries over to the next decode.

const bytes = new TextEncoder().encode("héllo");    // Uint8Array(6)
new TextDecoder().decode(bytes);                    // "héllo"

const dec = new TextDecoder("utf-8");
dec.decode(bytes.subarray(0, 2), { stream: true }); // "h"
dec.decode(bytes.subarray(2));                      // "éllo"

---

Other globals

P self

self: typeof globalThis

The global object, in every script and every worker, as in a browser, Deno, or Bun. In a worker, self.name is the worker's name.

F structuredClone

structuredClone<T>(value: T, options?: { transfer?: (MessagePort | ArrayBuffer)[] }): T

Returns a deep copy of value, made as a message to a worker is. See structuredClone.

O DOMException

new DOMException(message?: string, name?: string)

The web's DOMException: an Error that name classifies, "Error" by default. code is the web's legacy code for name, or 0. A value that cannot be cloned throws one named DataCloneError, with code 25.

F reportError

reportError(error: any): void

Reports error as an uncaught exception. The global fires an error event first, placed where error was made (or at the call, for a value with no stack). A listener that calls preventDefault(), or an onerror that returns true, handles it. Otherwise it prints as an uncaught exception, and then:

• In the script yeet run started, the script ends and yeet run exits non-zero, as in Bun and Deno.
• In a worker, the worker keeps running, as on the web. A dedicated worker's opener hears it on its Worker as an error event; see worker errors.

Throws a TypeError when called with no argument.

---

V8 built-ins

All standard ECMAScript built-ins are available: Array, Object, Map, Set, WeakMap, WeakSet, Promise, Proxy, Reflect, Symbol, BigInt, RegExp, Date, Error, JSON, Math, ArrayBuffer, TypedArrays, DataView, WeakRef, FinalizationRegistry, globalThis.

No ICU

This V8 build is compiled without ICU. The Intl.* namespace is unsafe to use. In particular, String.prototype.localeCompare throws RangeError: Internal error. Icu error. Use plain < / > comparisons for sorting and format numbers/dates manually.

---

What is NOT available

Node.js / Deno APIs

Missing API	Notes
process	No process.env, process.argv, process.exit(), etc. Use yeet.args for arguments.
require()	Use import / ES modules only.
__dirname / __filename	Not defined. Use import.meta.dirname / import.meta.filename.
Buffer	Use Uint8Array / ArrayBuffer.
fs	No file system access.
path / os	Not available.
child_process / exec	No subprocess spawning.
net / http / https	No socket or HTTP APIs.
setImmediate	Use queueMicrotask() or setTimeout(fn, 0).
performance	No performance.now().

Browser APIs

Missing API	Notes
fetch	No HTTP client. Data comes through yeet.graph.
WebSocket	Not available.
crypto / SubtleCrypto	Not available.
TextEncoderStream / TextDecoderStream	Not present. Use TextDecoder with { stream: true }.
URL / URLSearchParams	Not present.
AbortController / AbortSignal	Not present.
Event / EventTarget	Not globals. yeet:events exports Event, EventTarget, and ErrorEvent, which workers and message ports use.
SharedArrayBuffer / Atomics	No shared memory. Worker and SharedWorker exist, as separate isolates that talk over message ports; see Workers.
localStorage / sessionStorage	Not available.
document / DOM	No DOM.
requestAnimationFrame	Use setInterval.
XMLHttpRequest / FormData / Blob	Not present.
ReadableStream / WritableStream	No WHATWG streams.