docs: added explanation of passing appender module in config, and types

CHANGELOG.md

@@ -1,5 +1,9 @@
 # log4js-node changelog
 
+## 4.4.0
+* [Add option to pass appender module in config](https://github.com/log4js-node/log4js-node/pull/833) - thanks [@kaxelson](https://github.com/kaxelson)
+* [Updated dependencies](https://github.com/log4js-node/log4js-node/pull/900)
+
 ## 4.3.2
 * [Types for enableCallStack](https://github.com/log4js-node/log4js-node/pull/897) - thanks [@citrusjunoss](https://github.com/citrusjunoss)
 

docs/appenders.md

@@ -68,3 +68,16 @@ Log4js checks the following places (in this order) for appenders based on the ty
 4. relative to the process' current working directory: `require(process.cwd() + '/' + type)`
 
 If you want to write your own appender, read the [documentation](writing-appenders.md) first.
+
+## Advanced configuration
+If you've got a custom appender of your own, or are using webpack (or some other bundler), you may find it easier to pass
+in the appender module in the config instead of loading from the node.js require path. Here's an example:
+```javascript
+const myAppenderModule = {
+  configure: (config, layouts, findAppender, levels) => { /* ...your appender config... */ }
+};
+log4js.configure({
+  appenders: { custom: { type: myAppenderModule } },
+  categories: { default: { appenders: ['custom'], level: 'debug' } }
+});
+```

lib/appenders/index.js

@@ -42,8 +42,8 @@ const loadAppenderModule = (type, config) => coreAppenders.get(type)
 
 const createAppender = (name, config) => {
   const appenderConfig = config.appenders[name];
-  const appenderModule =
-    appenderConfig.type.configure ? appenderConfig.type : loadAppenderModule(appenderConfig.type, config);
+  const appenderModule = appenderConfig.type.configure
+    ? appenderConfig.type : loadAppenderModule(appenderConfig.type, config);
   configuration.throwExceptionIf(
     config,
     configuration.not(appenderModule),

types/log4js.d.ts

@@ -104,8 +104,8 @@ export interface CategoryFilterAppender {
 export interface NoLogFilterAppender {
   type: "noLogFilter";
   // the regular expression (or the regular expressions if you provide an array of values)
-  // will be used for evaluating the events to pass to the appender. 
-  // The events, which will match the regular expression, will be excluded and so not logged. 
+  // will be used for evaluating the events to pass to the appender.
+  // The events, which will match the regular expression, will be excluded and so not logged.
   exclude: string | string[];
   // the name of an appender, defined in the same configuration, that you want to filter.
 	appender: string;
@@ -237,10 +237,14 @@ export interface StandardOutputAppender {
 }
 
 export interface CustomAppender {
-	type: string;
+	type: string | AppenderModule;
 	[key: string]: any;
 }
 
+export interface AppenderModule {
+	configure: Function
+}
+
 export type Appender = CategoryFilterAppender
 	| ConsoleAppender
 	| FileAppender
@@ -253,7 +257,8 @@ export type Appender = CategoryFilterAppender
 	| RecordingAppender
 	| StandardErrorAppender
 	| StandardOutputAppender
-	| CustomAppender;
+	| CustomAppender
+	| AppenderModule;
 
 export interface Levels {
   ALL: Level;

types/test.ts

@@ -130,3 +130,9 @@ log4js.connectLogger(logger1, {
 log4js.connectLogger(logger2, {
   format: (req, _res, format) => format(`:remote-addr - ${req.id} - ":method :url HTTP/:http-version" :status :content-length ":referrer" ":user-agent"`)
 });
+
+//support for passing in an appender module
+log4js.configure({
+  appenders: { thing: { type: { configure: () => {} }}},
+  categories: { default: { appenders: ['thing'], level: 'debug'}}
+});