add splitChunks.minSizeReduction

declarations/WebpackOptions.d.ts

@@ -1751,6 +1751,10 @@ export interface OptimizationSplitChunksOptions {
 		 * Minimal size for the created chunk.
 		 */
 		minSize?: OptimizationSplitChunksSizes;
+		/**
+		 * Minimum size reduction due to the created chunk.
+		 */
+		minSizeReduction?: OptimizationSplitChunksSizes;
 	};
 	/**
 	 * Sets the template for the filename for created chunks.
@@ -1797,6 +1801,10 @@ export interface OptimizationSplitChunksOptions {
 	 * Minimal size for the created chunks.
 	 */
 	minSize?: OptimizationSplitChunksSizes;
+	/**
+	 * Minimum size reduction due to the created chunk.
+	 */
+	minSizeReduction?: OptimizationSplitChunksSizes;
 	/**
 	 * Give chunks created a name (chunks with equal name are merged).
 	 */
@@ -1877,6 +1885,10 @@ export interface OptimizationSplitChunksCacheGroup {
 	 * Minimal size for the created chunk.
 	 */
 	minSize?: OptimizationSplitChunksSizes;
+	/**
+	 * Minimum size reduction due to the created chunk.
+	 */
+	minSizeReduction?: OptimizationSplitChunksSizes;
 	/**
 	 * Give chunks for this cache group a name (chunks with equal name are merged).
 	 */

lib/optimize/SplitChunksPlugin.js

@@ -59,6 +59,7 @@ const MinMaxSizeWarning = require("./MinMaxSizeWarning");
  * @property {ChunkFilterFunction=} chunksFilter
  * @property {boolean=} enforce
  * @property {SplitChunksSizes} minSize
+ * @property {SplitChunksSizes} minSizeReduction
  * @property {SplitChunksSizes} minRemainingSize
  * @property {SplitChunksSizes} enforceSizeThreshold
  * @property {SplitChunksSizes} maxAsyncSize
@@ -80,6 +81,7 @@ const MinMaxSizeWarning = require("./MinMaxSizeWarning");
  * @property {GetName=} getName
  * @property {ChunkFilterFunction=} chunksFilter
  * @property {SplitChunksSizes} minSize
+ * @property {SplitChunksSizes} minSizeReduction
  * @property {SplitChunksSizes} minRemainingSize
  * @property {SplitChunksSizes} enforceSizeThreshold
  * @property {SplitChunksSizes} maxAsyncSize
@@ -132,6 +134,7 @@ const MinMaxSizeWarning = require("./MinMaxSizeWarning");
  * @property {ChunkFilterFunction} chunksFilter
  * @property {string[]} defaultSizeTypes
  * @property {SplitChunksSizes} minSize
+ * @property {SplitChunksSizes} minSizeReduction
  * @property {SplitChunksSizes} minRemainingSize
  * @property {SplitChunksSizes} enforceSizeThreshold
  * @property {SplitChunksSizes} maxInitialSize
@@ -336,6 +339,21 @@ const checkMinSize = (sizes, minSize) => {
 	return true;
 };
 
+/**
+ * @param {SplitChunksSizes} sizes the sizes
+ * @param {SplitChunksSizes} minSizeReduction the min sizes
+ * @param {number} chunkCount number of chunks
+ * @returns {boolean} true if there are sizes and all existing sizes are at least `minSizeReduction`
+ */
+const checkMinSizeReduction = (sizes, minSizeReduction, chunkCount) => {
+	for (const key of Object.keys(minSizeReduction)) {
+		const size = sizes[key];
+		if (size === undefined || size === 0) continue;
+		if (size * chunkCount < minSizeReduction[key]) return false;
+	}
+	return true;
+};
+
 /**
  * @param {SplitChunksSizes} sizes the sizes
  * @param {SplitChunksSizes} minSize the min sizes
@@ -548,6 +566,10 @@ const checkModuleLayer = (test, module) => {
  */
 const createCacheGroupSource = (options, key, defaultSizeTypes) => {
 	const minSize = normalizeSizes(options.minSize, defaultSizeTypes);
+	const minSizeReduction = normalizeSizes(
+		options.minSizeReduction,
+		defaultSizeTypes
+	);
 	const maxSize = normalizeSizes(options.maxSize, defaultSizeTypes);
 	return {
 		key,
@@ -556,6 +578,7 @@ const createCacheGroupSource = (options, key, defaultSizeTypes) => {
 		chunksFilter: normalizeChunksFilter(options.chunks),
 		enforce: options.enforce,
 		minSize,
+		minSizeReduction,
 		minRemainingSize: mergeSizes(
 			normalizeSizes(options.minRemainingSize, defaultSizeTypes),
 			minSize
@@ -594,6 +617,10 @@ module.exports = class SplitChunksPlugin {
 		];
 		const fallbackCacheGroup = options.fallbackCacheGroup || {};
 		const minSize = normalizeSizes(options.minSize, defaultSizeTypes);
+		const minSizeReduction = normalizeSizes(
+			options.minSizeReduction,
+			defaultSizeTypes
+		);
 		const maxSize = normalizeSizes(options.maxSize, defaultSizeTypes);
 
 		/** @type {SplitChunksOptions} */
@@ -601,6 +628,7 @@ module.exports = class SplitChunksPlugin {
 			chunksFilter: normalizeChunksFilter(options.chunks || "all"),
 			defaultSizeTypes,
 			minSize,
+			minSizeReduction,
 			minRemainingSize: mergeSizes(
 				normalizeSizes(options.minRemainingSize, defaultSizeTypes),
 				minSize
@@ -668,6 +696,10 @@ module.exports = class SplitChunksPlugin {
 			cacheGroupSource.minSize,
 			cacheGroupSource.enforce ? undefined : this.options.minSize
 		);
+		const minSizeReduction = mergeSizes(
+			cacheGroupSource.minSizeReduction,
+			cacheGroupSource.enforce ? undefined : this.options.minSizeReduction
+		);
 		const minRemainingSize = mergeSizes(
 			cacheGroupSource.minRemainingSize,
 			cacheGroupSource.enforce ? undefined : this.options.minRemainingSize
@@ -681,6 +713,7 @@ module.exports = class SplitChunksPlugin {
 			priority: cacheGroupSource.priority || 0,
 			chunksFilter: cacheGroupSource.chunksFilter || this.options.chunksFilter,
 			minSize,
+			minSizeReduction,
 			minRemainingSize,
 			enforceSizeThreshold,
 			maxAsyncSize: mergeSizes(
@@ -1244,6 +1277,14 @@ module.exports = class SplitChunksPlugin {
 					for (const [key, info] of chunksInfoMap) {
 						if (removeMinSizeViolatingModules(info)) {
 							chunksInfoMap.delete(key);
+						} else if (
+							!checkMinSizeReduction(
+								info.sizes,
+								info.cacheGroup.minSizeReduction,
+								info.chunks.size
+							)
+						) {
+							chunksInfoMap.delete(key);
 						}
 					}
 
@@ -1531,7 +1572,14 @@ module.exports = class SplitChunksPlugin {
 										chunksInfoMap.delete(key);
 										continue;
 									}
-									if (removeMinSizeViolatingModules(info)) {
+									if (
+										removeMinSizeViolatingModules(info) ||
+										!checkMinSizeReduction(
+											info.sizes,
+											info.cacheGroup.minSizeReduction,
+											info.chunks.size
+										)
+									) {
 										chunksInfoMap.delete(key);
 										continue;
 									}

schemas/WebpackOptions.json

@@ -2458,6 +2458,14 @@
             }
           ]
         },
+        "minSizeReduction": {
+          "description": "Minimum size reduction due to the created chunk.",
+          "oneOf": [
+            {
+              "$ref": "#/definitions/OptimizationSplitChunksSizes"
+            }
+          ]
+        },
         "name": {
           "description": "Give chunks for this cache group a name (chunks with equal name are merged).",
           "anyOf": [
@@ -2654,6 +2662,14 @@
                   "$ref": "#/definitions/OptimizationSplitChunksSizes"
                 }
               ]
+            },
+            "minSizeReduction": {
+              "description": "Minimum size reduction due to the created chunk.",
+              "oneOf": [
+                {
+                  "$ref": "#/definitions/OptimizationSplitChunksSizes"
+                }
+              ]
             }
           }
         },
@@ -2730,6 +2746,14 @@
             }
           ]
         },
+        "minSizeReduction": {
+          "description": "Minimum size reduction due to the created chunk.",
+          "oneOf": [
+            {
+              "$ref": "#/definitions/OptimizationSplitChunksSizes"
+            }
+          ]
+        },
         "name": {
           "description": "Give chunks created a name (chunks with equal name are merged).",
           "anyOf": [

test/Validation.test.js

@@ -453,7 +453,7 @@ describe("Validation", () => {
 		},
 		msg =>
 			expect(msg).toMatchInlineSnapshot(`
-			"Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.
+"Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.
  - configuration.optimization.splitChunks.cacheGroups should not be object { test, … }.
    -> Using the cacheGroup shorthand syntax with a cache group named 'test' is a potential config error
    Did you intent to define a cache group with a test instead?
@@ -462,9 +462,9 @@ describe("Validation", () => {
        test: ...
      }
    }.
-			   object { <key>: false | RegExp | string | function | object { automaticNameDelimiter?, chunks?, enforce?, enforceSizeThreshold?, filename?, idHint?, layer?, maxAsyncRequests?, maxAsyncSize?, maxInitialRequests?, maxInitialSize?, maxSize?, minChunks?, minRemainingSize?, minSize?, name?, priority?, reuseExistingChunk?, test?, type?, usedExports? } }
+   object { <key>: false | RegExp | string | function | object { automaticNameDelimiter?, chunks?, enforce?, enforceSizeThreshold?, filename?, idHint?, layer?, maxAsyncRequests?, maxAsyncSize?, maxInitialRequests?, maxInitialSize?, maxSize?, minChunks?, minRemainingSize?, minSize?, minSizeReduction?, name?, priority?, reuseExistingChunk?, test?, type?, usedExports? } }
    -> Assign modules to a cache group (modules from different cache groups are tried to keep in separate chunks, default categories: 'default', 'defaultVendors')."
-		`)
+`)
 	);
 
 	createTestCase(
@@ -661,11 +661,11 @@ describe("Validation", () => {
 			},
 			msg =>
 				expect(msg).toMatchInlineSnapshot(`
-			"Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.
+"Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.
  - configuration.optimization.splitChunks has an unknown property 'automaticNamePrefix'. These properties are valid:
-			   object { automaticNameDelimiter?, cacheGroups?, chunks?, defaultSizeTypes?, enforceSizeThreshold?, fallbackCacheGroup?, filename?, hidePathInfo?, maxAsyncRequests?, maxAsyncSize?, maxInitialRequests?, maxInitialSize?, maxSize?, minChunks?, minRemainingSize?, minSize?, name?, usedExports? }
+   object { automaticNameDelimiter?, cacheGroups?, chunks?, defaultSizeTypes?, enforceSizeThreshold?, fallbackCacheGroup?, filename?, hidePathInfo?, maxAsyncRequests?, maxAsyncSize?, maxInitialRequests?, maxInitialSize?, maxSize?, minChunks?, minRemainingSize?, minSize?, minSizeReduction?, name?, usedExports? }
    -> Options object for splitting chunks into smaller chunks."
-		`)
+`)
 		);
 	});
 });

test/__snapshots__/Cli.test.js.snap

@@ -4446,6 +4446,19 @@ Object {
     "multiple": false,
     "simpleType": "number",
   },
+  "optimization-split-chunks-fallback-cache-group-min-size-reduction": Object {
+    "configs": Array [
+      Object {
+        "description": "Size of the javascript part of the chunk.",
+        "multiple": false,
+        "path": "optimization.splitChunks.fallbackCacheGroup.minSizeReduction",
+        "type": "number",
+      },
+    ],
+    "description": "Size of the javascript part of the chunk.",
+    "multiple": false,
+    "simpleType": "number",
+  },
   "optimization-split-chunks-filename": Object {
     "configs": Array [
       Object {
@@ -4576,6 +4589,19 @@ Object {
     "multiple": false,
     "simpleType": "number",
   },
+  "optimization-split-chunks-min-size-reduction": Object {
+    "configs": Array [
+      Object {
+        "description": "Size of the javascript part of the chunk.",
+        "multiple": false,
+        "path": "optimization.splitChunks.minSizeReduction",
+        "type": "number",
+      },
+    ],
+    "description": "Size of the javascript part of the chunk.",
+    "multiple": false,
+    "simpleType": "number",
+  },
   "optimization-split-chunks-name": Object {
     "configs": Array [
       Object {

test/__snapshots__/StatsTestCases.basictest.js.snap

@@ -4292,6 +4292,37 @@ enforce-min-size:
   enforce-min-size (webpack x.x.x) compiled successfully"
 `;
 
+exports[`StatsTestCases should print correct stats for split-chunks-min-size-reduction 1`] = `
+"Entrypoint main 11.5 KiB = default/main.js
+chunk (runtime: main) default/async-d.js (async-d) 50 bytes <{179}> ={821}= [rendered]
+  > ./d ./index.js 4:0-47
+  ./d.js 50 bytes [built] [code generated]
+chunk (runtime: main) default/main.js (main) 245 bytes (javascript) 6.68 KiB (runtime) >{31}< >{334}< >{383}< >{449}< >{794}< >{821}< [entry] [rendered]
+  > ./ main
+  runtime modules 6.68 KiB 9 modules
+  ./index.js 245 bytes [built] [code generated]
+chunk (runtime: main) default/async-b.js (async-b) 176 bytes <{179}> [rendered]
+  > ./b ./index.js 2:0-47
+  ./b.js 50 bytes [built] [code generated]
+  ./node_modules/shared.js?1 126 bytes [dependent] [built] [code generated]
+chunk (runtime: main) default/async-c.js (async-c) 50 bytes <{179}> ={821}= [rendered]
+  > ./c ./index.js 3:0-47
+  ./c.js 50 bytes [built] [code generated]
+chunk (runtime: main) default/async-e.js (async-e) 50 bytes <{179}> ={821}= [rendered]
+  > ./e ./index.js 5:0-47
+  ./e.js 50 bytes [built] [code generated]
+chunk (runtime: main) default/async-a.js (async-a) 176 bytes <{179}> [rendered]
+  > ./a ./index.js 1:0-47
+  ./a.js 50 bytes [built] [code generated]
+  ./node_modules/shared.js?1 126 bytes [dependent] [built] [code generated]
+chunk (runtime: main) default/821.js (id hint: vendors) 126 bytes <{179}> ={31}= ={383}= ={449}= [rendered] split chunk (cache group: defaultVendors)
+  > ./c ./index.js 3:0-47
+  > ./d ./index.js 4:0-47
+  > ./e ./index.js 5:0-47
+  ./node_modules/shared.js?2 126 bytes [built] [code generated]
+webpack x.x.x compiled successfully"
+`;
+
 exports[`StatsTestCases should print correct stats for split-chunks-prefer-bigger-splits 1`] = `
 "Entrypoint main 11.2 KiB = default/main.js
 chunk (runtime: main) default/118.js 150 bytes <{179}> ={334}= ={383}= [rendered] split chunk (cache group: default)

test/statsCases/split-chunks-min-size-reduction/a.js

@@ -0,0 +1,2 @@
+import s from "shared?1";
+export default "a" + s;

test/statsCases/split-chunks-min-size-reduction/b.js

@@ -0,0 +1,2 @@
+import s from "shared?1";
+export default "b" + s;

test/statsCases/split-chunks-min-size-reduction/c.js

@@ -0,0 +1,2 @@
+import s from "shared?2";
+export default "c" + s;

test/statsCases/split-chunks-min-size-reduction/d.js

@@ -0,0 +1,2 @@
+import s from "shared?2";
+export default "c" + s;

test/statsCases/split-chunks-min-size-reduction/e.js

@@ -0,0 +1,2 @@
+import s from "shared?2";
+export default "c" + s;

test/statsCases/split-chunks-min-size-reduction/index.js

@@ -0,0 +1,5 @@
+import(/* webpackChunkName: "async-a" */ "./a");
+import(/* webpackChunkName: "async-b" */ "./b");
+import(/* webpackChunkName: "async-c" */ "./c");
+import(/* webpackChunkName: "async-d" */ "./d");
+import(/* webpackChunkName: "async-e" */ "./e");

test/statsCases/split-chunks-min-size-reduction/node_modules/shared.js

@@ -0,0 +1,3 @@
+// content content content content content content
+// content content content content content content
+export default "shared"

test/statsCases/split-chunks-min-size-reduction/webpack.config.js

@@ -0,0 +1,30 @@
+const stats = {
+	hash: false,
+	timings: false,
+	builtAt: false,
+	assets: false,
+	chunks: true,
+	chunkRelations: true,
+	chunkModules: true,
+	dependentModules: true,
+	chunkOrigins: true,
+	entrypoints: true,
+	modules: false
+};
+/** @type {import("../../../").Configuration} */
+module.exports = {
+	mode: "production",
+	entry: {
+		main: "./"
+	},
+	output: {
+		filename: "default/[name].js"
+	},
+	optimization: {
+		splitChunks: {
+			minSize: 0,
+			minSizeReduction: 300
+		}
+	},
+	stats
+};

types.d.ts

@@ -631,6 +631,7 @@ declare interface CacheGroupSource {
 	chunksFilter?: (chunk: Chunk) => boolean;
 	enforce?: boolean;
 	minSize: SplitChunksSizes;
+	minSizeReduction: SplitChunksSizes;
 	minRemainingSize: SplitChunksSizes;
 	enforceSizeThreshold: SplitChunksSizes;
 	maxAsyncSize: SplitChunksSizes;
@@ -7822,6 +7823,11 @@ declare interface OptimizationSplitChunksCacheGroup {
 	 */
 	minSize?: number | { [index: string]: number };
 
+	/**
+	 * Minimum size reduction due to the created chunk.
+	 */
+	minSizeReduction?: number | { [index: string]: number };
+
 	/**
 	 * Give chunks for this cache group a name (chunks with equal name are merged).
 	 */
@@ -7913,6 +7919,10 @@ declare interface OptimizationSplitChunksOptions {
 		 * Minimal size for the created chunk.
 		 */
 		minSize?: number | { [index: string]: number };
+		/**
+		 * Minimum size reduction due to the created chunk.
+		 */
+		minSizeReduction?: number | { [index: string]: number };
 	};
 
 	/**
@@ -7965,6 +7975,11 @@ declare interface OptimizationSplitChunksOptions {
 	 */
 	minSize?: number | { [index: string]: number };
 
+	/**
+	 * Minimum size reduction due to the created chunk.
+	 */
+	minSizeReduction?: number | { [index: string]: number };
+
 	/**
 	 * Give chunks created a name (chunks with equal name are merged).
 	 */
@@ -10726,6 +10741,7 @@ declare interface SplitChunksOptions {
 	chunksFilter: (chunk: Chunk) => boolean;
 	defaultSizeTypes: string[];
 	minSize: SplitChunksSizes;
+	minSizeReduction: SplitChunksSizes;
 	minRemainingSize: SplitChunksSizes;
 	enforceSizeThreshold: SplitChunksSizes;
 	maxInitialSize: SplitChunksSizes;