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Build Tool for Browser and Node Applications

npm version


$ npm install @sinclair/hammer -g


Create an index.html file

<!DOCTYPE html>
    <link href="index.css" rel="stylesheet" />
    <script src="index.tsx"></script>
    <img src="banner.png" />

Run Hammer

$ hammer build index.html



Hammer is a command line tool for browser and node application development. It provides a command line interface to trivially run both browser and node applications and offers appropriate watch and reload workflows for each environment. It is designed with rapid application development in mind and requires little to no configuration to use.

Hammer was written to consolidate several disparate tools related to monitoring node processes (nodemon), building from HTML (parcel), mono repository support (lerna, nx) and project automation (gulp, grunt). It takes esbuild as its only dependency and is as much concerned with build performance as it is with dramatically reducing the number of development dependencies required for modern web application development.

License MIT


Use the serve command to start a development server that reloads pages on save.

<!DOCTYPE html>
    <script type="module" src="index.tsx"></script>
    <h1>Hello World</h1>
$ hammer serve index.html


Use the run command to start a node process that restarts on save.

$ hammer run index.ts

$ hammer run "index.ts arg1 arg2" # use quotes to pass arguments

$ hammer run index.mts            # node esm modules supported via .mts


Use the watch command to start a compiler watch process only.

$ hammer watch worker.ts


Use the monitor command to execute shell commands on file change.

$ hammer monitor index.ts "deno run --allow-all index.ts"


Hammer provides a built-in task runner for automating various workflow at the command line. Tasks are created with JavaScript functions specified in a file named hammer.mjs. Hammer will search for the hammer.mjs file in the current working directory and setup a callable command line interface to each exported function. Hammer provides a global shell(...) function that can be used to start command line processes within each task. Additional functionality can be imported via ESM import. The following shows running a Hammer website and server watch process in parallel.

// file: hammer.mjs
export async function start() {
    await Promise.all([
        shell(`hammer serve apps/website/index.html --dist dist/website`),
        shell(`hammer run apps/server/index.ts --dist dist/server`)
$ hammer task start


In mono repository projects, you can import shared libraries by using TypeScript tsconfig.json path aliasing.

    index.ts    ───────────┐
  /website                 │
    index.html             │
    index.ts    ───────────┤ depends on
/libs                      │
  /shared                  │
    index.ts    <──────────┘

To enable website and server to import the shared library. Configure tsconfig.json in the project root as follows.

    "compilerOptions": {
        "baseUrl": ".",
        "paths": {
            "@libs/shared": ["libs/shared/index.ts"],

Once configured the server and website applications can import with the following.

import { Foo } from '@libs/shared'


Hammer provides the following command line interface.


   $ hammer run     <script path>     <...options>
   $ hammer build   <file or folder>  <...options>
   $ hammer watch   <file or folder>  <...options>
   $ hammer serve   <file or folder>  <...options>
   $ hammer monitor <file or folder>  <shell command>
   $ hammer task    <name>            <...arguments>
   $ hammer version
   $ hammer help


   --target      targets     The es build targets.
   --platform    platform    The target platform.
   --dist        directory   The target directory.
   --port        port        The port to listen on.
   --external    packages    Omits external packages.
   --esm                     Use esm module target.
   --minify                  Minifies the output.
   --sourcemap               Generate sourcemaps.
   --sabs                    (serve) Enable shared array buffer.
   --cors                    (serve) Enable cors.