Class Logger

Structured, level-classified logging — and nothing else.

Each line is one JSON object emitted through the matching console.* method, so the runtime's log collector records the native level and keeps the fields searchable. Nothing here aggregates — that is TelemetrySink, a separate capability, because a sink samples at volume and is the wrong place for lines that have to be read back verbatim.

Remarks

The threshold comes from the surface registered by configure, and LOG_LEVEL in the environment overrides it per deployment, so staging can run at debug without a code change.

Retention is the runtime's business, not this class's — it writes lines and stops there. Whether they are kept, and for how long, is a deployment setting wherever the process runs.

Example

const log = Logger.fromEnv(env, { service: 'ArticleService' })
log.info('article created', { id })

Author

Bayu Dwiyan Satria

Version

1.0.0

Since

1.0.0

Index

Constructors

`Private`constructor

new Logger(threshold: number, context: LogContext): Logger
Constructs a Logger.
Parameters
- threshold: number
  Minimum weight to emit.
- context: LogContext
  Fields repeated on every line.
Returns Logger
- Defined in src/core/Logger.ts:72

Properties

`Private` `Readonly`context

context: LogContext

Fields repeated on every line.

`Private` `Readonly`threshold

threshold: number

Minimum weight a line must carry to be emitted.

Methods

child

child(context: LogContext): Logger
Derives a logger with extra context, sharing this one's threshold.
Parameters
- context: LogContext
  Fields to add to every line.
Returns Logger
The derived logger.
- Defined in src/core/Logger.ts:103

debug

debug(message: string, data?: Record<string, unknown>): void
Emits a debug line.
Parameters
- message: string
  What happened.
- Optionaldata: Record<string, unknown>
  Structured detail.
Returns void
- Defined in src/core/Logger.ts:113

`Private`emit

emit(level: LogLevel, message: string, data?: Record<string, unknown>): void
Writes one line through the console method matching its level.
Parameters
- level: LogLevel
  Severity of the line.
- message: string
  What happened.
- Optionaldata: Record<string, unknown>
  Structured detail.
Returns void
- Defined in src/core/Logger.ts:154

error

error(message: string, data?: Record<string, unknown>): void
Emits an error line.
Parameters
- message: string
  What happened.
- Optionaldata: Record<string, unknown>
  Structured detail.
Returns void
- Defined in src/core/Logger.ts:143

`Static`fromEnv

fromEnv(env: { LOG_LEVEL?: string }, context?: LogContext): Logger
Builds a logger for the current environment.
Parameters
- env: { LOG_LEVEL?: string }
  Anything carrying an optional LOG_LEVEL. Tolerates null.
- context: LogContext = {}
  Fields to repeat on every line.
Returns Logger
A logger honouring the configured (or LOG_LEVEL) threshold.

Remarks
The parameter is structural rather than a named environment type. All this needs is a possible LOG_LEVEL, so asking for exactly that keeps the kernel free of any platform's environment shape — a runtime's Env object, a process.env, or a bare object literal all satisfy it.
- Defined in src/core/Logger.ts:90

info

info(message: string, data?: Record<string, unknown>): void
Emits an info line.
Parameters
- message: string
  What happened.
- Optionaldata: Record<string, unknown>
  Structured detail.
Returns void
- Defined in src/core/Logger.ts:123

`Private` `Static`parse

parse(value?: string): LogLevel
Parses a level name, ignoring anything unrecognised.
Parameters
- Optionalvalue: string
  The candidate level name.
Returns LogLevel
The level, or null when the value is not one.
- Defined in src/core/Logger.ts:188

`Private` `Static`serialize

serialize(data: Record<string, unknown>): Record<string, unknown>
Makes a data payload serialisable — Error values in particular, which JSON.stringify would otherwise flatten to {}.
Parameters
- data: Record<string, unknown>
  The payload to convert.
Returns Record<string, unknown>
The payload with errors expanded to message and stack.
- Defined in src/core/Logger.ts:201

warn

warn(message: string, data?: Record<string, unknown>): void
Emits a warn line.
Parameters
- message: string
  What happened.
- Optionaldata: Record<string, unknown>
  Structured detail.
Returns void
- Defined in src/core/Logger.ts:133

Class Logger

Remarks

Example

Author

Version

Since

Index

Constructors

Properties

Methods

Constructors

Privateconstructor

Parameters

Returns Logger

Properties

Private Readonlycontext

Private Readonlythreshold

Methods

child

Parameters

Returns Logger

debug

Parameters

Returns void

Privateemit

Parameters

Returns void

error

Parameters

Returns void

StaticfromEnv

Parameters

Returns Logger

Remarks

info

Parameters

Returns void

Private Staticparse

Parameters

Returns LogLevel

Private Staticserialize

Parameters

Returns Record<string, unknown>

warn

Parameters

Returns void

Settings

On This Page

`Private`constructor

`Private` `Readonly`context

`Private` `Readonly`threshold

`Private`emit

`Static`fromEnv

`Private` `Static`parse

`Private` `Static`serialize