Oscar-ren/sideEffects

show the webpack sideEffects config effect

sideEffects Demo

run

npm run build

entry

src/sideEffects.js

reference

• src/module/big-module there is no sideEffects config
• src/module/big-module-with-flag this have sideEffects config
• lodash-es@4.17.10

env

• node v8.5.0
• npm v6.0.0
• webpack @4.10.2

build result

reason

babel transform the module to commonjs, webpack can't treeshaking the commonjs module.

we should config below, let webpack deal with the row code, since the webpack@2, webpack can deal with es6 import and export default syntax.

{
  "presets": [
    ["env", {
      "modules": false
    }]
  ]
}