Change the naming convention for LogMessage internal message field.

Taking advantage of the new LogMessageFormatter return type, the
ConsoleLogAppender logs the formatted message as-is if it is a string,
but when processing structured data inserts a string summary consisting
of the message level, scope, and message summary or method. The full
object is still logged to the console as well for inspection.

eslint.config.mjs

@@ -25,6 +25,14 @@ const customTypescriptConfig = {
   rules: {
     'linebreak-style': ['error', 'unix'],
     quotes: ['error', 'single', { avoidEscape: true }],
+    semi: ['error', 'never'],
+    '@typescript-eslint/no-unused-vars': ['error', {
+      'args': 'all',
+      'argsIgnorePattern': '^_',
+      'caughtErrorsIgnorePattern': '^_',
+      'destructuredArrayIgnorePattern': '^_',
+      'varsIgnorePattern': '^_',
+    }],
   },
 }
 
@@ -51,4 +59,10 @@ export default [
   eslintJs.configs.recommended,
   ...recommendedTypeScriptConfigs,
   customTypescriptConfig,
+  {
+    rules: {
+      quotes: ['error', 'single', { avoidEscape: true }],
+      semi: ['error', 'never'],
+    },
+  },
 ]

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@jdbernard/logging",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "Simple Javascript logging service.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

src/console-log-appender.ts

@@ -3,12 +3,23 @@ import {
   LogLevel,
   LogMessage,
   LogMessageFormatter,
-} from './log-message';
-import { LogAppender } from './log-appender';
+} from "./log-message";
+import { LogAppender } from "./log-appender";
 
+/**
+ * A log appender that writes log messages to the console. The behavior of the
+ * log appender can be configured with a threshold level and a message
+ * formatter.
+ *
+ * When the message formatter returns a string value, that value is logged to
+ * the console as-is. When the message formatter returns an object, a summary
+ * string is logged to the console, followed by the object itself. This allows
+ * logs to be easily read in the console, while still providing the structured
+ * data for inspection in the browser's developer tools.
+ */
 export class ConsoleLogAppender implements LogAppender {
   public threshold = LogLevel.ALL;
-  public formatter: LogMessageFormatter = flattenMessage
+  public formatter: LogMessageFormatter = flattenMessage;
 
   constructor(threshold?: LogLevel, formatter?: LogMessageFormatter) {
     if (threshold) {
@@ -27,17 +38,13 @@ export class ConsoleLogAppender implements LogAppender {
     let logMethod = console.log;
     switch (msg.level) {
       case LogLevel.ALL:
-        logMethod = console.log;
-        break;
       case LogLevel.TRACE:
+      case LogLevel.LOG:
         logMethod = console.log;
         break;
       case LogLevel.DEBUG:
         logMethod = console.debug;
         break;
-      case LogLevel.LOG:
-        logMethod = console.log;
-        break;
       case LogLevel.INFO:
         logMethod = console.info;
         break;
@@ -50,12 +57,25 @@ export class ConsoleLogAppender implements LogAppender {
         break;
     }
 
-    const strMsg = this.formatter(msg);
+    const fmtMsg = this.formatter(msg);
 
-    if (msg.error || msg.stacktrace) {
-      logMethod(strMsg, msg.error ?? msg.stacktrace);
+    if (typeof fmtMsg === "string") {
+      if (msg.error || msg.stacktrace) {
+        logMethod(fmtMsg, msg.error ?? msg.stacktrace);
+      } else {
+        logMethod(fmtMsg);
+      }
     } else {
-      logMethod(strMsg);
+      const { message, _error, _stacktrace, ...rest } = fmtMsg;
+      const summary = `${LogLevel[msg.level]} -- ${msg.scope}: ${
+        message ?? fmtMsg.method
+      }\n`;
+
+      if (msg.error || msg.stacktrace) {
+        logMethod(summary, msg.error ?? msg.stacktrace, rest);
+      } else {
+        logMethod(summary, rest);
+      }
     }
   }
 }

src/log-message.ts

@@ -1,4 +1,4 @@
-import { omit } from './util'
+import { omit } from "./util";
 
 export enum LogLevel {
   ALL = 0,
@@ -25,7 +25,7 @@ export function parseLogLevel(
 export interface LogMessage {
   scope: string;
   level: LogLevel;
-  message: string | Record<string, unknown>;
+  msg: string | Record<string, unknown>;
   stacktrace?: string;
   error?: Error;
   timestamp: Date;
@@ -54,31 +54,33 @@ export type FlattenedLogMessage = Record<string, unknown>;
  * ```
  */
 export function flattenMessage(msg: LogMessage): FlattenedLogMessage {
-  if (typeof msg.message === 'string') {
+  if (typeof msg.msg === "string") {
     return { ...msg, level: LogLevel[msg.level] };
   } else {
-    const { message, ...rest } = msg;
+    const { msg, ...rest } = msg;
     return {
-      ...omit(message, [
-        'scope',
-        'level',
-        'stacktrace',
-        'error',
-        'timestamp',
+      ...omit(msg, [
+        "scope",
+        "level",
+        "stacktrace",
+        "error",
+        "timestamp",
       ]),
       ...rest,
       level: LogLevel[msg.level],
     };
   }
 }
-export type LogMessageFormatter = (msg: LogMessage) => string | FlattenedLogMessage;
+export type LogMessageFormatter = (
+  msg: LogMessage,
+) => string | FlattenedLogMessage;
 
 export function structuredLogMessageFormatter(msg: LogMessage): string {
   return JSON.stringify(flattenMessage(msg));
 }
 
 export function simpleTextLogMessageFormatter(msg: LogMessage): string {
-  return `[${msg.scope}] - ${msg.level}: ${msg.message}`;
+  return `[${msg.scope}] - ${msg.level}: ${msg.msg}`;
 }
 
 export default LogMessage;