@bazel/terser

Terser rules for Bazel

WARNING: this is beta-quality software. Breaking changes are likely. Not recommended for production use without expert support.

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.

Your WORKSPACE should declare a yarn_install or npm_install rule named npm. It should then install the rules found in the npm packages using the install_bazel_dependencies function. See https://github.com/bazelbuild/rules_nodejs/#quickstart

This causes the @bazel/terser package to be installed as a Bazel workspace named npm_bazel_terser.

Installing with self-managed dependencies

If you didn't use the yarn_install or npm_install rule to create an npm workspace, you'll have to declare a rule in your root BUILD.bazel file to execute terser:

# Create a terser rule to use in terser_minified#terser_bin
# attribute when using self-managed dependencies
nodejs_binary(
    name = "terser_bin",
    entry_point = "//:node_modules/terser/bin/uglifyjs",
    # Point bazel to your node_modules to find the entry point
    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.

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.

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.

sourcemap

(Boolean): Whether to produce a .js.map output

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

Changelog

0.42.1 (2019-11-27)

To upgrade:

http_archive(
    name = "build_bazel_rules_nodejs",
    sha256 = "c612d6b76eaa17540e8b8c806e02701ed38891460f9ba3303f4424615437887a",
    urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/0.42.1/rules_nodejs-0.42.1.tar.gz"],
)

and run yarn upgrade --scope @bazel to update all your @bazel-scoped npm packages to the latest versions. (or manually do the npm equivalent - they don't have a way to update a scope)

New stuff

In 0.41.0 we noted that a feature for inserting <script> and <link> tags was dropped from ts_devserver and pkg_web but the replacement wasn't available. Now it is thanks to @jbedard who published a standalone npm package html-insert-assets. You can see how it's wired in the examples.

If you waited to upgrade before, now you should.

Bug Fixes

• @npm//foobar:foobar__files target no longer includes nested node_modules (#1390) (a13f2b6)
• allow files in protractor data attribute (3feb13c)
• builtin: $(RULEDIR) npm_package_bin expansion should always be the root output directory (b494974)
• builtin: locations arg of npm_package_bin should result in separate argv (242379f)
• builtin: use correct genrule-style make vars (77039b1)
• examples: kotlin example server working (adf6934)

BREAKING CHANGES

• builtin: We fixed npm_package_bin and all rules generated by it, to match genrule behavior as documented at https://docs.bazel.build/versions/master/be/make-variables.html#predefined_genrule_variables This means that usage of the $@ shortcut to refer to the output directory should now be $(@D) when output_dir=True and you can now use $@ to refer to the location of a single output