Add asObjectBindingsOnly, allowing write to receive only the bindings as object

browser.js

@@ -109,6 +109,7 @@ function pino (opts) {
     transmit,
     serialize,
     asObject: opts.browser.asObject,
+    asObjectBindingsOnly: opts.browser.asObjectBindingsOnly,
     formatters: opts.browser.formatters,
     levels,
     timestamp: getTimeFunction(opts),
@@ -317,7 +318,7 @@ function createWrap (self, opts, rootLogger, level) {
         argsIsSerialized = true
       }
       if (opts.asObject || opts.formatters) {
-        write.call(proto, asObject(this, level, args, ts, opts))
+        write.call(proto, ...asObject(this, level, args, ts, opts))
       } else write.apply(proto, args)
 
       if (opts.transmit) {
@@ -347,6 +348,10 @@ function asObject (logger, level, args, ts, opts) {
   const argsCloned = args.slice()
   let msg = argsCloned[0]
   const logObject = {}
+
+  let lvl = (logger._childLevel | 0) + 1
+  if (lvl < 1) lvl = 1
+
   if (ts) {
     logObject.time = ts
   }
@@ -358,19 +363,28 @@ function asObject (logger, level, args, ts, opts) {
     logObject.level = logger.levels.values[level]
   }
 
-  let lvl = (logger._childLevel | 0) + 1
-  if (lvl < 1) lvl = 1
-  // deliberate, catching objects, arrays
-  if (msg !== null && typeof msg === 'object') {
-    while (lvl-- && typeof argsCloned[0] === 'object') {
-      Object.assign(logObject, argsCloned.shift())
+  if (opts.asObjectBindingsOnly) {
+    if (msg !== null && typeof msg === 'object') {
+      while (lvl-- && typeof argsCloned[0] === 'object') {
+        Object.assign(logObject, argsCloned.shift())
+      }
     }
-    msg = argsCloned.length ? format(argsCloned.shift(), argsCloned) : undefined
-  } else if (typeof msg === 'string') msg = format(argsCloned.shift(), argsCloned)
-  if (msg !== undefined) logObject[opts.messageKey] = msg
 
-  const formattedLogObject = logObjectFormatter(logObject)
-  return formattedLogObject
+    const formattedLogObject = logObjectFormatter(logObject)
+    return [formattedLogObject, ...argsCloned]
+  } else {
+    // deliberate, catching objects, arrays
+    if (msg !== null && typeof msg === 'object') {
+      while (lvl-- && typeof argsCloned[0] === 'object') {
+        Object.assign(logObject, argsCloned.shift())
+      }
+      msg = argsCloned.length ? format(argsCloned.shift(), argsCloned) : undefined
+    } else if (typeof msg === 'string') msg = format(argsCloned.shift(), argsCloned)
+    if (msg !== undefined) logObject[opts.messageKey] = msg
+
+    const formattedLogObject = logObjectFormatter(logObject)
+    return [formattedLogObject]
+  }
 }
 
 function applySerializers (args, serialize, serializers, stdErrSerialize) {

docs/browser.md

@@ -27,6 +27,21 @@ pino.info('hi') // creates and logs {msg: 'hi', level: 30, time: <ts>}
 
 When `write` is set, `asObject` will always be `true`.
 
+### `asObjectBindingsOnly` (Boolean)
+
+```js
+const pino = require('pino')({browser: {asObjectBindingsOnly: true}})
+```
+
+The `asObjectBindingsOnly` is similar to `asObject` but will keep the message
+and arguments unformatted, this allows to defer formatting the message to the
+actual call to `console` methods, where browsers then have richer formatting in
+their devtools then when pino will format the message to a string first.
+
+```js
+pino.info('hello %s', 'world') // creates and logs {level: 30, time: <ts>}, 'hello %s', 'world'
+```
+
 ### `formatters` (Object)
 
 An object containing functions for formatting the shape of the log lines. When provided, it enables the logger to produce a pino-like log object with customized formatting. Currently, it supports formatting for the `level` object only.

test/browser.test.js

@@ -165,6 +165,7 @@ test('opts.browser.asObject logs pino-like object to console', ({ end, ok, is })
   instance.info('test')
   end()
 })
+
 test('opts.browser.asObject uses opts.messageKey in logs', ({ end, ok, is }) => {
   const messageKey = 'message'
   const instance = require('../browser')({
@@ -183,6 +184,25 @@ test('opts.browser.asObject uses opts.messageKey in logs', ({ end, ok, is }) =>
   end()
 })
 
+test('opts.browser.asObjectBindingsOnly passes the bindings but keep the message unformatted', ({ end, ok, is, deepEqual }) => {
+  const messageKey = 'message'
+  const instance = require('../browser')({
+    messageKey,
+    browser: {
+      asObjectBindingsOnly: true,
+      write: function (o, msg, ...args) {
+        is(o.level, 30)
+        ok(o.time)
+        is(msg, 'test %s')
+        deepEqual(args, ['foo'])
+      }
+    }
+  })
+
+  instance.info('test %s', 'foo')
+  end()
+})
+
 test('opts.browser.formatters (level) logs pino-like object to console', ({ end, ok, is }) => {
   const info = console.info
   console.info = function (o) {