7.3 KiB
7.3 KiB
Info
This example illustrates webpack's algorithm for automatic deduplication using optimization.splitChunks.
This example application contains 7 pages, each of them importing 1-3 modules from the node_modules folder (vendor libs) and 0-3 modules from the stuff folder (application modules). In reallity an application is probably more complex, but the same mechanisms apply.
The following configuration is used:
optimization.splitChunks.chunks: "all"- This opt-in into automatic splitting of initial chunks which is off by defaultoptimization.splitChunks.maxInitial/AsyncRequests: 20- This opt-in into a HTTP2 optimized splitting mode by increasing the allowed amount of requests. Browser only supports 6 requests in parallel for HTTP1.1.
Interpreting the result
pageA.jsthe normal output files for the entrypointpageAvendors~pageD~pageE~pageF~pageG.jsvendor libs shared by these pages extracted into a separate output file when larger then the threshold in sizevendors~pageA.jsvendors only used by a single page but larger than the threshold in sizepageA~pageD~pageF.jsapplication modules shared by these pages and larger than the threshold in size
The threshold is here 40 bytes, but by default (in a real application) 30kb.
Some modules are intentially duplicated, i. e. ./stuff/s4.js is shared by pageA and pageC, but it's the only shared module so no separate output file is created because it would be smaller than the threshold. A separate request (which comes with an overhead and worsen gzipping) is not worth the extra bytes.
Note: decreasing maxInitial/AsyncRequest will increase duplication further to reduce the number of requests. Duplication doesn't affect initial page load, it only affects download size of navigations to other pages of the application.
webpack.config.js
module.exports = {
// mode: "development || "production",
entry: {
pageA: "./pages/a",
pageB: "./pages/b",
pageC: "./pages/c",
pageD: "./pages/d",
pageE: "./pages/e",
pageF: "./pages/f",
pageG: "./pages/g"
},
optimization: {
splitChunks: {
chunks: "all",
maxInitialRequests: 20, // for HTTP2
maxAsyncRequests: 20, // for HTTP2
minSize: 40 // for example only: chosen to match 2 modules
// omit minSize in real use case to use the default of 30kb
}
}
};
Production mode
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 4.29.6
Asset Size Chunks Chunk Names
pageA.js 1.55 KiB 4 [emitted] pageA
pageA~pageD~pageF.js 156 bytes 1 [emitted] pageA~pageD~pageF
pageB.js 1.65 KiB 5 [emitted] pageB
pageC.js 1.65 KiB 6 [emitted] pageC
pageD.js 1.55 KiB 7 [emitted] pageD
pageE.js 1.54 KiB 8 [emitted] pageE
pageF.js 1.55 KiB 9 [emitted] pageF
pageG.js 1.53 KiB 10 [emitted] pageG
vendors~pageA.js 122 bytes 11 [emitted] vendors~pageA
vendors~pageA~pageB~pageC.js 178 bytes 2 [emitted] vendors~pageA~pageB~pageC
vendors~pageB.js 122 bytes 12 [emitted] vendors~pageB
vendors~pageC.js 122 bytes 13 [emitted] vendors~pageC
vendors~pageD~pageE~pageF.js 180 bytes 3 [emitted] vendors~pageD~pageE~pageF
vendors~pageD~pageE~pageF~pageG.js 119 bytes 0 [emitted] vendors~pageD~pageE~pageF~pageG
Entrypoint pageA = vendors~pageA~pageB~pageC.js vendors~pageA.js pageA~pageD~pageF.js pageA.js
Entrypoint pageB = vendors~pageA~pageB~pageC.js vendors~pageB.js pageB.js
Entrypoint pageC = vendors~pageA~pageB~pageC.js vendors~pageC.js pageC.js
Entrypoint pageD = vendors~pageD~pageE~pageF~pageG.js vendors~pageD~pageE~pageF.js pageA~pageD~pageF.js pageD.js
Entrypoint pageE = vendors~pageD~pageE~pageF~pageG.js vendors~pageD~pageE~pageF.js pageE.js
Entrypoint pageF = vendors~pageD~pageE~pageF~pageG.js vendors~pageD~pageE~pageF.js pageA~pageD~pageF.js pageF.js
Entrypoint pageG = vendors~pageD~pageE~pageF~pageG.js pageG.js
chunk {0} vendors~pageD~pageE~pageF~pageG.js (vendors~pageD~pageE~pageF~pageG) 43 bytes ={1}= ={3}= ={7}= ={8}= ={9}= ={10}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageD~pageE~pageF~pageG)
> ./pages/d pageD
> ./pages/e pageE
> ./pages/f pageF
> ./pages/g pageG
1 module
chunk {1} pageA~pageD~pageF.js (pageA~pageD~pageF) 62 bytes ={0}= ={2}= ={3}= ={4}= ={7}= ={9}= ={11}= [initial] [rendered] split chunk (cache group: default) (name: pageA~pageD~pageF)
> ./pages/a pageA
> ./pages/d pageD
> ./pages/f pageF
[4] ./stuff/s2.js 31 bytes {1} [built]
[5] ./stuff/s3.js 31 bytes {1} [built]
chunk {2} vendors~pageA~pageB~pageC.js (vendors~pageA~pageB~pageC) 86 bytes ={1}= ={4}= ={5}= ={6}= ={11}= ={12}= ={13}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageA~pageB~pageC)
> ./pages/a pageA
> ./pages/b pageB
> ./pages/c pageC
2 modules
chunk {3} vendors~pageD~pageE~pageF.js (vendors~pageD~pageE~pageF) 86 bytes ={0}= ={1}= ={7}= ={8}= ={9}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageD~pageE~pageF)
> ./pages/d pageD
> ./pages/e pageE
> ./pages/f pageF
2 modules
chunk {4} pageA.js (pageA) 137 bytes ={1}= ={2}= ={11}= [entry] [rendered]
> ./pages/a pageA
[6] ./stuff/s4.js 31 bytes {4} {6} [built]
[10] ./pages/a.js 106 bytes {4} [built]
chunk {5} pageB.js (pageB) 199 bytes ={2}= ={12}= [entry] [rendered]
> ./pages/b pageB
[0] ./stuff/s1.js 31 bytes {5} {7} {9} {10} [built]
[7] ./stuff/s7.js 31 bytes {5} {8} [built]
[12] ./pages/b.js 106 bytes {5} [built]
[14] ./stuff/s8.js 31 bytes {5} [built]
chunk {6} pageC.js (pageC) 199 bytes ={2}= ={13}= [entry] [rendered]
> ./pages/c pageC
[6] ./stuff/s4.js 31 bytes {4} {6} [built]
[15] ./pages/c.js 106 bytes {6} [built]
[17] ./stuff/s5.js 31 bytes {6} [built]
[18] ./stuff/s6.js 31 bytes {6} [built]
chunk {7} pageD.js (pageD) 137 bytes ={0}= ={1}= ={3}= [entry] [rendered]
> ./pages/d pageD
[0] ./stuff/s1.js 31 bytes {5} {7} {9} {10} [built]
[19] ./pages/d.js 106 bytes {7} [built]
chunk {8} pageE.js (pageE) 93 bytes ={0}= ={3}= [entry] [rendered]
> ./pages/e pageE
[7] ./stuff/s7.js 31 bytes {5} {8} [built]
[20] ./pages/e.js 62 bytes {8} [built]
chunk {9} pageF.js (pageF) 137 bytes ={0}= ={1}= ={3}= [entry] [rendered]
> ./pages/f pageF
[0] ./stuff/s1.js 31 bytes {5} {7} {9} {10} [built]
[21] ./pages/f.js 106 bytes {9} [built]
chunk {10} pageG.js (pageG) 67 bytes ={0}= [entry] [rendered]
> ./pages/g pageG
[0] ./stuff/s1.js 31 bytes {5} {7} {9} {10} [built]
[22] ./pages/g.js 36 bytes {10} [built]
chunk {11} vendors~pageA.js (vendors~pageA) 43 bytes ={1}= ={2}= ={4}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageA)
> ./pages/a pageA
1 module
chunk {12} vendors~pageB.js (vendors~pageB) 43 bytes ={2}= ={5}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageB)
> ./pages/b pageB
1 module
chunk {13} vendors~pageC.js (vendors~pageC) 43 bytes ={2}= ={6}= [initial] [rendered] split chunk (cache group: vendors) (name: vendors~pageC)
> ./pages/c pageC
1 module