console
js/globals/console.ts
Console globals available as globalThis.console.
The console API provides synchronous diagnostic output for programs and runtime tooling. Methods write formatted text directly to stdout or stderr, so logging is available before stream globals or the event loop are fully initialized.
Values are formatted with a small inspector that understands primitives,
arrays, plain objects, errors, dates, maps, sets, typed arrays, and circular
references. String-first calls support printf-style substitutions such as
%s, %d, %f, %o, %O, %c, and %%.
Grouping indents later output until groupEnd() is called. Timers and
counters are stored per label, matching the shape of the WHATWG Console API
while keeping terminal-only operations such as clear() and timeStamp()
as no-ops.
console.group('request');
console.log({ method: 'GET', url: '/health' });
console.time('work');
console.timeEnd('work');
console.groupEnd();Console Standard: https://console.spec.whatwg.org/
Interfaces
interface Console {
The console object installed on globalThis.console.
Console methods synchronously format their arguments and write one line to
stdout or stderr. Formatting supports common JavaScript values, % style
substitutions in string-first calls, indentation groups, timers, and
counters.
The runtime installs a singleton implementing this interface on
globalThis.console, so no import is needed:
console.log('user %s logged in', 'ada'); // stdout: user ada logged in
console.error(new Error('boom')); // stderr: [error] Error: boom ...
console.time('parse');
JSON.parse('{"large": "payload"}');
console.timeEnd('parse'); // stdout: parse: 0.42ms
console.count('requests'); // stdout: requests: 1Methods
log(...args: unknown[]): void
Write a formatted line to stdout.
info(...args: unknown[]): void
Write a formatted informational line to stdout.
debug(...args: unknown[]): void
Write a formatted debug line to stdout.
warn(...args: unknown[]): void
Write a formatted warning line to stderr with a warning prefix.
error(...args: unknown[]): void
Write a formatted error line to stderr with an error prefix.
assert(condition: unknown, ...args: unknown[]): void
Write an assertion failure to stderr when condition is falsy.
dir(obj: unknown, opts?: {
depth?: number;
colors?: boolean;
}): void
Inspect obj and write the result to stdout.
depth controls object and array recursion. colors is accepted for
compatibility but ignored because console output is plain text.
table(data: unknown): void
Write table data to stdout.
Fino currently prints JSON when possible and falls back to normal object inspection for values that cannot be serialized.
group(...args: unknown[]): void
Write an optional heading and indent subsequent console output.
groupCollapsed(...args: unknown[]): void
Write an optional heading and indent subsequent output.
This is equivalent to group() in the terminal runtime because there is no
DevTools UI that can collapse groups.
groupEnd(): void
End the current indentation group.
time(label?: string): void
Start or replace a timer for label.
Omitting label uses the label 'default'. Starting a timer that already
exists silently restarts it.
timeEnd(label?: string): void
Print the elapsed time for label to stdout and remove the timer.
If no timer with that label exists, a [warn] line is written to stderr
instead.
timeLog(label?: string, ...args: unknown[]): void
Print the elapsed time for label without removing the timer.
Extra arguments are formatted and appended after the elapsed time. If no
timer with that label exists, a [warn] line is written to stderr instead.
count(label?: string): void
Increment and print the counter for label.
Omitting label uses the label 'default'. The first call for a label
prints 1.
countReset(label?: string): void
Reset the counter for label.
If no counter with that label exists, a [warn] line is written to stderr.
clear(): void
Clear the console when an interactive console is available.
This is a no-op in Fino's terminal runtime.
trace(...args: unknown[]): void
Write a stack trace to stdout with optional formatted leading text.
dirxml(...args: unknown[]): void
Write XML-like diagnostic output.
Because Fino has no DOM renderer, this delegates to normal console formatting.
timeStamp(label?: string): void
Record a performance timestamp when a DevTools timeline is available.
This is a no-op in Fino's terminal runtime.
Constants
const console: Console
Runtime console singleton exposed as globalThis.console.
Methods write directly to stdout or stderr through internal libc bindings. Formatting is intentionally small and synchronous so console works before stream globals or the event loop are fully initialized.
console.log('ready');
console.warn('slow path');