with

Signature

with(opts: ZylogFormatOptions): this

Description

The with method returns a proxy-like interface that applies specific formatting options to exactly one subsequent logging call. This is extremely useful for adding temporary context (like Request IDs or User IDs) without mutating the global logger state.

Tip

This is the preferred way to implement contextual logging in middleware or event handlers.

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Examples

Adding Request Context

Commonly used in HTTP servers to trace logs back to a specific request.

function handleRequest(req, res) {
  const reqId = req.headers['x-request-id'];

  zylog.with({ prefix: `req:${reqId}` }).info('Processing payment');

  // The next call returns to the default prefix
  zylog.info('Normal log line');
}

Temporary Formatting Change

Change the separator or line ending for a single complex log.

zylog.with({ sep: ' -> ', prefix: 'DEBUG' }).trace('Step 1', 'Step 2', 'Step 3');

Chaining with JSON

Combine with json() for structured, contextual output.

zylog.with({ prefix: 'AUDIT' }).json({ action: 'delete', userId: 501 }, 'warn');