Syntax Downgrade and Polyfill
By default, Farm will downgrade to ES2017
(native support async/await
) and inject necessary polyfills
automatically in production mode.
By default, Farm won't do transformation and inject polyfills for modules under node_modules/
, if you need to downgrade syntax and inject polyfills for node_modules/
you can use compilation.presetEnv.include
.
Configuring targetEnv
Farm provide a normalized output.targetEnv
option to configure the target execution environment of your application. Farm will perform properly syntax downgrade
and polyfill injection
for your target environment automatically. For example:
Farm will compile your application to legacy browsers(ES5):
- Compile all
Js/Jsx/Ts/Tsx
modules toES5
, and inject all polyfills(Promise, regenerator-runtime and so on). - Add prefix for all
css/scss/less
modules, for example,--webkit-
.
Farm supports many normalized targetEnv
options like browser-modern
, browser-es2017
, browser-es2015
, node16
, node-legacy
, etc. By default, targetEnv
is browser-es2017
. Refer to output.targetEnv
.
You may need to install core-js@3
or regeneration-runtime
manually if polyfill is needed. Try run pnpm add core-js
if you met something error like can not resolve 'core-js/modules/xxx'
Configuring Syntax and Polyfill Separately
Internally, targetEnv
just presets of presetEnv
, script.target
and css.prefixer
. You can configure them more precisely if you need.
Configuring presetEnv
You can use compilation.presetEnv
to custom syntax downgrade and polyfill injection. By default all modules under node_modules
will be ignored. Using include
to add extra modules that need to be polyfilled.
Note that if your project does not require browser compatibility, you can use set a looser value for targets
, then less polyfills will be injected and output sizes will be smaller.
Refer to compilation.presetEnv for more options.
Configuring script.target
script.target
is used to control the target env when generate code. If you want to downgrade your project to ES5
, you should set both: