esbuild

What are esbuild's main functionalities?

require('esbuild').build({
  entryPoints: ['app.js'],
  bundle: true,
  outfile: 'out.js'
}).catch(() => process.exit(1))

require('esbuild').build({
  entryPoints: ['app.js'],
  minify: true,
  outfile: 'out.js'
}).catch(() => process.exit(1))

require('esbuild').build({
  entryPoints: ['app.ts'],
  bundle: true,
  outfile: 'out.js'
}).catch(() => process.exit(1))

require('esbuild').serve({
  servedir: 'public',
  port: 8000
}, {
  entryPoints: ['app.js'],
  bundle: true,
  outfile: 'public/out.js'
}).then(server => {
  // Server started
})

0.19.10

• Fix glob imports in TypeScript files (#3319)

  This release fixes a problem where bundling a TypeScript file containing a glob import could emit a call to a helper function that doesn't exist. The problem happened because esbuild's TypeScript transformation removes unused imports (which is required for correctness, as they may be type-only imports) and esbuild's glob import transformation wasn't correctly marking the imported helper function as used. This wasn't caught earlier because most of esbuild's glob import tests were written in JavaScript, not in TypeScript.

• Fix require() glob imports with bundling disabled (#3546)

  Previously require() calls containing glob imports were incorrectly transformed when bundling was disabled. All glob imports should only be transformed when bundling is enabled. This bug has been fixed.

• Fix a panic when transforming optional chaining with define (#3551, #3554)

  This release fixes a case where esbuild could crash with a panic, which was triggered by using define to replace an expression containing an optional chain. Here is an example:

  // Original code
  console.log(process?.env.SHELL)
  
  // Old output (with --define:process.env={})
  /* panic: Internal error (while parsing "<stdin>") */
  
  // New output (with --define:process.env={})
  var define_process_env_default = {};
  console.log(define_process_env_default.SHELL);
  

  This fix was contributed by @hi-ogawa.

• Work around a bug in node's CommonJS export name detector (#3544)

  The export names of a CommonJS module are dynamically-determined at run time because CommonJS exports are properties on a mutable object. But the export names of an ES module are statically-determined at module instantiation time by using import and export syntax and cannot be changed at run time.

  When you import a CommonJS module into an ES module in node, node scans over the source code to attempt to detect the set of export names that the CommonJS module will end up using. That statically-determined set of names is used as the set of names that the ES module is allowed to import at module instantiation time. However, this scan appears to have bugs (or at least, can cause false positives) because it doesn't appear to do any scope analysis. Node will incorrectly consider the module to export something even if the assignment is done to a local variable instead of to the module-level exports object. For example:

  // confuseNode.js
  exports.confuseNode = function(exports) {
    // If this local is called "exports", node incorrectly
    // thinks this file has an export called "notAnExport".
    exports.notAnExport = function() {
    };
  };
  

  You can see that node incorrectly thinks the file confuseNode.js has an export called notAnExport when that file is loaded in an ES module context:

  $ node -e 'import("./confuseNode.js").then(console.log)'
  [Module: null prototype] {
    confuseNode: [Function (anonymous)],
    default: { confuseNode: [Function (anonymous)] },
    notAnExport: undefined
  }
  

  To avoid this, esbuild will now rename local variables that use the names exports and module when generating CommonJS output for the node platform.

• Fix the return value of esbuild's super() shim (#3538)

  Some people write constructor methods that use the return value of super() instead of using this. This isn't too common because TypeScript doesn't let you do that but it can come up when writing JavaScript. Previously esbuild's class lowering transform incorrectly transformed the return value of super() into undefined. With this release, the return value of super() will now be this instead:

  // Original code
  class Foo extends Object {
    field
    constructor() {
      console.log(typeof super())
    }
  }
  new Foo
  
  // Old output (with --target=es6)
  class Foo extends Object {
    constructor() {
      var __super = (...args) => {
        super(...args);
        __publicField(this, "field");
      };
      console.log(typeof __super());
    }
  }
  new Foo();
  
  // New output (with --target=es6)
  class Foo extends Object {
    constructor() {
      var __super = (...args) => {
        super(...args);
        __publicField(this, "field");
        return this;
      };
      console.log(typeof __super());
    }
  }
  new Foo();
  

• Terminate the Go GC when esbuild's stop() API is called (#3552)

  If you use esbuild with WebAssembly and pass the worker: false flag to esbuild.initialize(), then esbuild will run the WebAssembly module on the main thread. If you do this within a Deno test and that test calls esbuild.stop() to clean up esbuild's resources, Deno may complain that a setTimeout() call lasted past the end of the test. This happens when the Go is in the middle of a garbage collection pass and has scheduled additional ongoing garbage collection work. Normally calling esbuild.stop() will terminate the web worker that the WebAssembly module runs in, which will terminate the Go GC, but that doesn't happen if you disable the web worker with worker: false.

  With this release, esbuild will now attempt to terminate the Go GC in this edge case by calling clearTimeout() on these pending timeouts.

• Apply /* @__NO_SIDE_EFFECTS__ */ on tagged template literals (#3511)

  Tagged template literals that reference functions annotated with a @__NO_SIDE_EFFECTS__ comment are now able to be removed via tree-shaking if the result is unused. This is a convention from Rollup. Here is an example:

  // Original code
  const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b })
  html`<a>remove</a>`
  x = html`<b>keep</b>`
  
  // Old output (with --tree-shaking=true)
  const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b });
  html`<a>remove</a>`;
  x = html`<b>keep</b>`;
  
  // New output (with --tree-shaking=true)
  const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b });
  x = html`<b>keep</b>`;
  

  Note that this feature currently only works within a single file, so it's not especially useful. This feature does not yet work across separate files. I still recommend using @__PURE__ annotations instead of this feature, as they have wider tooling support. The drawback of course is that @__PURE__ annotations need to be added at each call site, not at the declaration, and for non-call expressions such as template literals you need to wrap the expression in an IIFE (immediately-invoked function expression) to create a call expression to apply the @__PURE__ annotation to.

• Publish builds for IBM AIX PowerPC 64-bit (#3549)

  This release publishes a binary executable to npm for IBM AIX PowerPC 64-bit, which means that in theory esbuild can now be installed in that environment with npm install esbuild. This hasn't actually been tested yet. If you have access to such a system, it would be helpful to confirm whether or not doing this actually works.