Terser rules for Bazel
The Terser rules run the Terser JS minifier with Bazel.
Wraps the Terser CLI documented at https://github.com/terser-js/terser#command-line-usage
Installation
Add the @bazel/terser
npm package to your devDependencies
in package.json
.
Installing with self-managed dependencies
If you didn't use the yarn_install
or npm_install
rule, you'll have to declare a rule in your root BUILD.bazel
file to execute terser:
nodejs_binary(
name = "terser_bin",
entry_point = "//:node_modules/terser/bin/uglifyjs",
node_modules = ["//:node_modules"],
)
terser_minified
Run the terser minifier.
Typical example:
load("@npm//@bazel/terser:index.bzl", "terser_minified")
terser_minified(
name = "out.min",
src = "input.js",
config_file = "terser_config.json",
)
Note that the name
attribute determines what the resulting files will be called.
So the example above will output out.min.js
and out.min.js.map
(since sourcemap
defaults to true
).
If the input is a directory, then the output will also be a directory, named after the name
attribute.
Usage
terser_minified(name, args, config_file, debug, sourcemap, src, terser_bin)
name
(name, mandatory): A unique name for this target.
args
(List of strings): Additional command line arguments to pass to terser.
Terser only parses minify() args from the config file so additional arguments such as --comments
may
be passed to the rule using this attribute. See https://github.com/terser/terser#command-line-usage for the
full list of terser CLI options.
Defaults to []
config_file
(label): A JSON file containing Terser minify() options.
This is the file you would pass to the --config-file argument in terser's CLI.
https://github.com/terser-js/terser#minify-options documents the content of the file.
Bazel will make a copy of your config file, treating it as a template.
Run bazel with --subcommands
to see the path to the copied file.
If you use the magic strings "bazel_debug"
or "bazel_no_debug"
, these will be
replaced with true
and false
respecting the value of the debug
attribute
or the --compilation_mode=dbg
bazel flag.
For example,
{
"compress": {
"arrows": "bazel_no_debug"
}
}
Will disable the arrows
compression setting when debugging.
If config_file
isn't supplied, Bazel will use a default config file.
Defaults to //@bazel/terser:terser_config.default.json
debug
(Boolean): Configure terser to produce more readable output.
Instead of setting this attribute, consider using debugging compilation mode instead
bazel build --compilation_mode=dbg //my/terser:target
so that it only affects the current build.
Defaults to False
sourcemap
(Boolean): Whether to produce a .js.map output
Defaults to True
src
(label, mandatory): File(s) to minify.
Can be a .js file, a rule producing .js files as its default output, or a rule producing a directory of .js files.
Note that you can pass multiple files to terser, which it will bundle together.
If you want to do this, you can pass a filegroup here.
terser_bin
(label): An executable target that runs Terser
Defaults to //@bazel/terser/bin:terser