s-l-t-r

Something Like a Task Runner.

• Run multiple commands in sequence or in parallel.
• Simple. Lightweight. No dependencies.
• Might be an alternative to NPM scripts (node_modules/.bin is automatically addded to PATH).
• Write your own script in JS and construct any tree structure for defining the execution order.
• Create a router so that you can run different commands according to arguments.
• Check summary of execution results and see where it took time or where it failed.

GitHub: https://github.com/fal-works/s-l-t-r

Install

npm install -D @fal-works/s-l-t-r

How to Use

Define Commands

Here we will write a script and make a tree structure consisting of Command elements.

• Use cmd() for defining a Command with a single command line.
• Use seq() or par() for defining a grouping Command that runs multiple child Commands.
  seq() for sequence, par() for parallel. They can be nested as well.

For example, a script for building the library s-l-t-r itself (say build.js) would look like this:

// build.js

/** import */
const s_l_t_r = require("@fal-works/s-l-t-r");
const { cmd, seq, par } = s_l_t_r; // functions for creating command elements
const { cleandir } = s_l_t_r.builtin; // built-in functions for specific purposes

/** prepare commands used frequently */
const lint = (files) => cmd("eslint", "--fix", files);

/** clean-up files in parallel */
const clean = par(cleandir("lib"), cleandir("types")).rename("clean");

/** emit files into lib/types */
const emit = cmd("tsc", "--skipLibCheck");

/** format files in parallel */
const format = par(lint("lib/**/*.js"), lint("types/**/*.ts")).rename("format");

/** do all of the above in sequence */
const build = seq(clean, emit, format).rename("build");

Something more:

• seq() and par() accept also any command line string values.
• Use cmdEx() for creating a Command from any async function.
• Use ignoreFailure() method if you want to run subsequent commands whether the command in question succeeds or not.

Run

Use run() to start executing any Command:

// build.js

/* ...(see above)... */

s_l_t_r.run(build);

Now you can simply run the script with Node.js:

# on the CLI or NPM script
node build.js

Routing

As an alternative to the top-level run() function,
create a router so you can receive any key and run different Commands:

// build.js

/* ...(see above)... */

/**
 * This router accepts the keys: "clean", "emit", "format" or "build",
 * otherwise it prints the registered mapping between keys and commands.
 */
const router = s_l_t_r.tools.createRouter({ clean, emit, format, build });

const CLI_ARGUMENT = process.argv[2];
router.run(CLI_ARGUMENT);

Now you can run the script passing any key that specifies the Command to be executed:

# on the CLI or NPM script
node build.js clean

Result Summary

When run() completes, it outputs a summary of the execution results.

It looks like this:

--         | [seq] build
--         |   [par] clean
ok   0.01s |     cleandir lib
ok   0.01s |     cleandir types
ok   1.30s |   tsc
--         |   [par] format
ok   1.49s |     eslint --fix lib/**/*.js
ok   1.24s |     eslint --fix types/**/*.ts

...or can also be flattend by changing the config:

sltr.config.setResultSummaryType("list"); // default: "tree"

which looks like this:

ok   0.01s | cleandir lib
ok   0.01s | cleandir types
ok   1.32s | tsc
ok   1.49s | eslint --fix lib/**/*.js
ok   1.23s | eslint --fix types/**/*.ts

You can also change the display in the summary for each Command individually:

• Use rename() method for changing the display name.
• Use hide() method to just hide it.
• Use collapse() method to collapse a grouping command (seq() or par()) and hide its children.

Other

The quiet mode suppresses log messages and only the final result (1 line, whether completed or not) is printed.

sltr.config.setQuiet();