diff --git a/lib/APIPlugin.js b/lib/APIPlugin.js
index 0a7e6888f..bfefb29a1 100644
--- a/lib/APIPlugin.js
+++ b/lib/APIPlugin.js
@@ -10,9 +10,10 @@ const {
 	toConstantDependencyWithWebpackRequire,
 	evaluateToString
 } = require("./JavascriptParserHelpers");
+const NullFactory = require("./NullFactory");
 const ConstDependency = require("./dependencies/ConstDependency");
 
-const NullFactory = require("./NullFactory");
+/** @typedef {import("./Compiler")} Compiler */
 
 /* eslint-disable camelcase */
 const REPLACEMENTS = {
@@ -37,6 +38,11 @@ const REPLACEMENT_TYPES = {
 /* eslint-enable camelcase */
 
 class APIPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"APIPlugin",
diff --git a/lib/AutomaticPrefetchPlugin.js b/lib/AutomaticPrefetchPlugin.js
index 1422185a5..84c76aa79 100644
--- a/lib/AutomaticPrefetchPlugin.js
+++ b/lib/AutomaticPrefetchPlugin.js
@@ -14,7 +14,7 @@ const PrefetchDependency = require("./dependencies/PrefetchDependency");
 class AutomaticPrefetchPlugin {
 	/**
 	 * Apply the plugin
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/CompatibilityPlugin.js b/lib/CompatibilityPlugin.js
index 35aa6c782..909ca200a 100644
--- a/lib/CompatibilityPlugin.js
+++ b/lib/CompatibilityPlugin.js
@@ -14,7 +14,7 @@ const NullFactory = require("./NullFactory");
 class CompatibilityPlugin {
 	/**
 	 * Apply the plugin
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/ContextExclusionPlugin.js b/lib/ContextExclusionPlugin.js
index d46512f66..da51e30b2 100644
--- a/lib/ContextExclusionPlugin.js
+++ b/lib/ContextExclusionPlugin.js
@@ -17,7 +17,7 @@ class ContextExclusionPlugin {
 
 	/**
 	 * Apply the plugin
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/DelegatedPlugin.js b/lib/DelegatedPlugin.js
index 46037ad92..e79a8e088 100644
--- a/lib/DelegatedPlugin.js
+++ b/lib/DelegatedPlugin.js
@@ -10,11 +10,18 @@ const NullFactory = require("./NullFactory");
 const DelegatedExportsDependency = require("./dependencies/DelegatedExportsDependency");
 const DelegatedSourceDependency = require("./dependencies/DelegatedSourceDependency");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class DelegatedPlugin {
 	constructor(options) {
 		this.options = options;
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"DelegatedPlugin",
diff --git a/lib/EvalSourceMapDevToolPlugin.js b/lib/EvalSourceMapDevToolPlugin.js
index 314f9f763..6de6b8075 100644
--- a/lib/EvalSourceMapDevToolPlugin.js
+++ b/lib/EvalSourceMapDevToolPlugin.js
@@ -24,7 +24,7 @@ class EvalSourceMapDevToolPlugin {
 	}
 
 	/**
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/ExternalsPlugin.js b/lib/ExternalsPlugin.js
index 6b28a6b95..ec22929c1 100644
--- a/lib/ExternalsPlugin.js
+++ b/lib/ExternalsPlugin.js
@@ -7,11 +7,18 @@
 
 const ExternalModuleFactoryPlugin = require("./ExternalModuleFactoryPlugin");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class ExternalsPlugin {
 	constructor(type, externals) {
 		this.type = type;
 		this.externals = externals;
 	}
+
+	/**
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compile.tap("ExternalsPlugin", ({ normalModuleFactory }) => {
 			new ExternalModuleFactoryPlugin(this.type, this.externals).apply(
diff --git a/lib/FunctionModulePlugin.js b/lib/FunctionModulePlugin.js
index 16d8fbfc6..112fc6e6b 100644
--- a/lib/FunctionModulePlugin.js
+++ b/lib/FunctionModulePlugin.js
@@ -7,7 +7,14 @@
 
 const FunctionModuleTemplatePlugin = require("./FunctionModuleTemplatePlugin");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class FunctionModulePlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap("FunctionModulePlugin", compilation => {
 			new FunctionModuleTemplatePlugin({
diff --git a/lib/IgnorePlugin.js b/lib/IgnorePlugin.js
index 31b449a6f..20fb0c04e 100644
--- a/lib/IgnorePlugin.js
+++ b/lib/IgnorePlugin.js
@@ -82,7 +82,7 @@ class IgnorePlugin {
 	}
 
 	/**
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/JsonModulesPlugin.js b/lib/JsonModulesPlugin.js
index 9aa77d086..f52387685 100644
--- a/lib/JsonModulesPlugin.js
+++ b/lib/JsonModulesPlugin.js
@@ -9,7 +9,14 @@ const JavascriptModulesPlugin = require("./JavascriptModulesPlugin");
 const JsonGenerator = require("./JsonGenerator");
 const JsonParser = require("./JsonParser");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class JsonModulesPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"JsonModulesPlugin",
diff --git a/lib/ModuleProfile.js b/lib/ModuleProfile.js
index c2e64ef95..86d651c6f 100644
--- a/lib/ModuleProfile.js
+++ b/lib/ModuleProfile.js
@@ -62,12 +62,16 @@ class ModuleProfile {
 		this.storing = this.storingEndTime - this.storingStartTime;
 	}
 
+	/**
+	 * Merge this profile into another one
+	 * @param {ModuleProfile} realProfile the profile to merge into
+	 * @returns {void}
+	 */
 	mergeInto(realProfile) {
 		if (this.factory > realProfile.additionalFactories)
 			realProfile.additionalFactories = this.factory;
 		if (this.integration > realProfile.additionalIntegration)
 			realProfile.additionalIntegration = this.integration;
-		return realProfile;
 	}
 }
 
diff --git a/lib/NoEmitOnErrorsPlugin.js b/lib/NoEmitOnErrorsPlugin.js
index 9b02526a1..a84eb56c7 100644
--- a/lib/NoEmitOnErrorsPlugin.js
+++ b/lib/NoEmitOnErrorsPlugin.js
@@ -5,7 +5,14 @@
 
 "use strict";
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class NoEmitOnErrorsPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.shouldEmit.tap("NoEmitOnErrorsPlugin", compilation => {
 			if (compilation.getStats().hasErrors()) return false;
diff --git a/lib/NodeStuffPlugin.js b/lib/NodeStuffPlugin.js
index e50ed4f13..5b63cc3a6 100644
--- a/lib/NodeStuffPlugin.js
+++ b/lib/NodeStuffPlugin.js
@@ -18,6 +18,7 @@ const CachedConstDependency = require("./dependencies/CachedConstDependency");
 const ModuleDecoratorDependency = require("./dependencies/ModuleDecoratorDependency");
 
 /** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
+/** @typedef {import("./Compiler")} Compiler */
 /** @typedef {import("./Dependency")} Dependency */
 /** @typedef {import("./DependencyTemplates")} DependencyTemplates */
 /** @typedef {import("./RuntimeTemplate")} RuntimeTemplate */
@@ -30,6 +31,11 @@ class NodeStuffPlugin {
 		this.options = options;
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		const options = this.options;
 		compiler.hooks.compilation.tap(
diff --git a/lib/NormalModuleReplacementPlugin.js b/lib/NormalModuleReplacementPlugin.js
index 5fcd5a0b4..e7eb9ec35 100644
--- a/lib/NormalModuleReplacementPlugin.js
+++ b/lib/NormalModuleReplacementPlugin.js
@@ -7,12 +7,25 @@
 
 const path = require("path");
 
+/** @typedef {import("./Compiler")} Compiler */
+/** @typedef {function(TODO): void} ModuleReplacer */
+
 class NormalModuleReplacementPlugin {
+	/**
+	 * Create an instance of the plugin
+	 * @param {RegExp} resourceRegExp the resource matcher
+	 * @param {string|ModuleReplacer} newResource the resource replacement
+	 */
 	constructor(resourceRegExp, newResource) {
 		this.resourceRegExp = resourceRegExp;
 		this.newResource = newResource;
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		const resourceRegExp = this.resourceRegExp;
 		const newResource = this.newResource;
diff --git a/lib/PrefetchPlugin.js b/lib/PrefetchPlugin.js
index 01af601f3..b0648c744 100644
--- a/lib/PrefetchPlugin.js
+++ b/lib/PrefetchPlugin.js
@@ -7,16 +7,24 @@
 
 const PrefetchDependency = require("./dependencies/PrefetchDependency");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class PrefetchPlugin {
 	constructor(context, request) {
-		if (!request) {
-			this.request = context;
-		} else {
+		if (request) {
 			this.context = context;
 			this.request = request;
+		} else {
+			this.context = null;
+			this.request = context;
 		}
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"PrefetchPlugin",
diff --git a/lib/RequireJsStuffPlugin.js b/lib/RequireJsStuffPlugin.js
index c963d4095..976382d1a 100644
--- a/lib/RequireJsStuffPlugin.js
+++ b/lib/RequireJsStuffPlugin.js
@@ -12,7 +12,14 @@ const {
 const NullFactory = require("./NullFactory");
 const ConstDependency = require("./dependencies/ConstDependency");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 module.exports = class RequireJsStuffPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"RequireJsStuffPlugin",
diff --git a/lib/TemplatedPathPlugin.js b/lib/TemplatedPathPlugin.js
index b78935c5f..817e570e8 100644
--- a/lib/TemplatedPathPlugin.js
+++ b/lib/TemplatedPathPlugin.js
@@ -8,6 +8,7 @@
 const Module = require("./Module");
 
 /** @typedef {import("./Compilation").PathData} PathData */
+/** @typedef {import("./Compiler")} Compiler */
 
 const REGEXP_HASH = /\[hash(?::(\d+))?\]/gi,
 	REGEXP_CHUNKHASH = /\[chunkhash(?::(\d+))?\]/gi,
@@ -131,6 +132,11 @@ const replacePathVariables = (path, data) => {
 };
 
 class TemplatedPathPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap("TemplatedPathPlugin", compilation => {
 			const mainTemplate = compilation.mainTemplate;
diff --git a/lib/UseStrictPlugin.js b/lib/UseStrictPlugin.js
index a46641b48..d2bfd6fe7 100644
--- a/lib/UseStrictPlugin.js
+++ b/lib/UseStrictPlugin.js
@@ -11,7 +11,7 @@ const ConstDependency = require("./dependencies/ConstDependency");
 
 class UseStrictPlugin {
 	/**
-	 * @param {Compiler} compiler Webpack Compiler
+	 * @param {Compiler} compiler the compiler instance
 	 * @returns {void}
 	 */
 	apply(compiler) {
diff --git a/lib/WarnCaseSensitiveModulesPlugin.js b/lib/WarnCaseSensitiveModulesPlugin.js
index ad51a0e37..0be4f258c 100644
--- a/lib/WarnCaseSensitiveModulesPlugin.js
+++ b/lib/WarnCaseSensitiveModulesPlugin.js
@@ -7,7 +7,14 @@
 
 const CaseSensitiveModulesWarning = require("./CaseSensitiveModulesWarning");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class WarnCaseSensitiveModulesPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.compilation.tap(
 			"WarnCaseSensitiveModulesPlugin",
diff --git a/lib/WarnDeprecatedOptionPlugin.js b/lib/WarnDeprecatedOptionPlugin.js
index 331c8b086..518e33455 100644
--- a/lib/WarnDeprecatedOptionPlugin.js
+++ b/lib/WarnDeprecatedOptionPlugin.js
@@ -7,13 +7,26 @@
 
 const WebpackError = require("./WebpackError");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class WarnDeprecatedOptionPlugin {
+	/**
+	 * Create an instance of the plugin
+	 * @param {string} option the target option
+	 * @param {string | number} value the deprecated option value
+	 * @param {string} suggestion the suggestion replacement
+	 */
 	constructor(option, value, suggestion) {
 		this.option = option;
 		this.value = value;
 		this.suggestion = suggestion;
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.thisCompilation.tap(
 			"WarnDeprecatedOptionPlugin",
diff --git a/lib/WarnNoModeSetPlugin.js b/lib/WarnNoModeSetPlugin.js
index 2d5ce404d..b8685f039 100644
--- a/lib/WarnNoModeSetPlugin.js
+++ b/lib/WarnNoModeSetPlugin.js
@@ -7,7 +7,14 @@
 
 const NoModeWarning = require("./NoModeWarning");
 
+/** @typedef {import("./Compiler")} Compiler */
+
 class WarnNoModeSetPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
 	apply(compiler) {
 		compiler.hooks.thisCompilation.tap("WarnNoModeSetPlugin", compilation => {
 			compilation.warnings.push(new NoModeWarning());