CLJS DevTools Configuration

You can enable/disable desired features and configure other aspects of cljs-devtools.

Configuration can be done on multiple levels (later overrides former levels):

1. defaults
2. compiler options
3. environmental variables
4. programmatically

Configuration via defaults

Here is the list of default configuration keys.

Configuration via compiler options

You can specify a config map in your project.clj or build.boot under ClojureScript compiler options.

For example:

...
:compiler {
  :output-to       "..."
  :output-dir      "..."
  :main            ...
  :preloads        [devtools.preload ...]
  :external-config {
    :devtools/config {
      :features-to-install    [:formatters :hints]
      :fn-symbol              "F"
      :print-config-overrides true}}
  ...}

This overrides default :features-to-install, sets custom :fn-symbol and instructs cljs-devtools to print overridden config values during installation.

Configuration via environmental variables

We use binaryage/env-config library to allow configuration overrides via environmental variables. Common prefix for our configuration variables is CLJS_DEVTOOLS.

For example, in a Bash shell you can do this to achieve configuration matching the config map above:

lein clean
env CLJS_DEVTOOLS/FN_SYMBOL=F \
  CLJS_DEVTOOLS/PRINT_CONFIG_OVERRIDES=true \
  CLJS_DEVTOOLS/FEATURES_TO_INSTALL="~[:formatters :hints]" \
  lein cljsbuild once

Please note that environmental variables are retrieved during compilation in a macro expansion. So proper environment must be present during ClojureScript compilation and you have to clear compilation caches after changing the environment.

Programmatic configuration

When installed manually, you can pass a list of desired features to enable into devtools.core/install! call or use devtools.core/set-pref! to override individual default config keys prior calling install! from devtools.core namespace.

This explicit init code would be equivalent to the config map above.

(ns your-project.devtools
  (:require [devtools.core :as devtools]))

(devtools/set-pref! :fn-symbol "F")
(devtools/set-pref! :print-config-overrides true)
(devtools/install! [:formatters :hints])

Please note that most configuration keys can be changed dynamically even after cljs-devtools installation. For example styling options can be redefined temporarily for desired styling tweaks isolated for a single console.log call.

Here is the list of default configuration keys.