v0.27.2

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• Allow import path specifiers starting with #/ (#​4361)

  Previously the specification for package.json disallowed import path specifiers starting with #/, but this restriction has recently been relaxed and support for it is being added across the JavaScript ecosystem. One use case is using it for a wildcard pattern such as mapping #/* to ./src/* (previously you had to use another character such as #_* instead, which was more confusing). There is some more context in nodejs/node#49182.

  This change was contributed by @​hybrist.

• Automatically add the -webkit-mask prefix (#​4357, #​4358)

  This release automatically adds the -webkit- vendor prefix for the mask CSS shorthand property:

  /* Original code */
  main {
   mask: url(x.png) center/5rem no-repeat
  }
  /* Old output (with --target=chrome110) */
  main {
   mask: url(x.png) center/5rem no-repeat;
  }
  /* New output (with --target=chrome110) */
  main {
   -webkit-mask: url(x.png) center/5rem no-repeat;
   mask: url(x.png) center/5rem no-repeat;
  }

  This change was contributed by @​BPJEnnova.

• Additional minification of switch statements (#​4176, #​4359)

  This release contains additional minification patterns for reducing switch statements. Here is an example:

  // Original code
  switch (x) {
   case 0:
   foo()
   break
   case 1:
   default:
   bar()
  }
  // Old output (with --minify)
  switch(x){case 0:foo();break;case 1:default:bar()}
  // New output (with --minify)
  x===0?foo():bar();

• Forbid using declarations inside switch clauses (#​4323)

  This is a rare change to remove something that was previously possible. The Explicit Resource Management proposal introduced using declarations. These were previously allowed inside case and default clauses in switch statements. This had well-defined semantics and was already widely implemented (by V8, SpiderMonkey, TypeScript, esbuild, and others). However, it was considered to be too confusing because of how scope works in switch statements, so it has been removed from the specification. This edge case will now be a syntax error. See tc39/proposal-explicit-resource-management#215 and rbuckton/ecma262#14 for details.

  Here is an example of code that is no longer allowed:

  switch (mode) {
   case 'read':
   using readLock = db.read()
   return readAll(readLock)
   case 'write':
   using writeLock = db.write()
   return writeAll(writeLock)
  }

  That code will now have to be modified to look like this instead (note the additional { and } block statements around each case body):

  switch (mode) {
   case 'read': {
   using readLock = db.read()
   return readAll(readLock)
   }
   case 'write': {
   using writeLock = db.write()
   return writeAll(writeLock)
   }
  }

  This is not being released in one of esbuild's breaking change releases since this feature hasn't been finalized yet, and esbuild always tracks the current state of the specification (so esbuild's previous behavior was arguably incorrect).

v0.27.1

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• Fix bundler bug with var nested inside if (#​4348)

  This release fixes a bug with the bundler that happens when importing an ES module using require (which causes it to be wrapped) and there's a top-level var inside an if statement without being wrapped in a { ... } block (and a few other conditions). The bundling transform needed to hoist these var declarations outside of the lazy ES module wrapper for correctness. See the issue for details.

• Fix minifier bug with for inside try inside label (#​4351)

  This fixes an old regression from version v0.21.4. Some code was introduced to move the label inside the try statement to address a problem with transforming labeled for await loops to avoid the await (the transformation involves converting the for await loop into a for loop and wrapping it in a try statement). However, it introduces problems for cross-compiled JVM code that uses all three of these features heavily. This release restricts this transform to only apply to for loops that esbuild itself generates internally as part of the for await transform. Here is an example of some affected code:

  // Original code
  d: {
   e: {
   try {
   while (1) { break d }
   } catch { break e; }
   }
  }
  // Old output (with --minify)
  a:try{e:for(;;)break a}catch{break e}
  // New output (with --minify)
  a:e:try{for(;;)break a}catch{break e}

• Inline IIFEs containing a single expression (#​4354)

  Previously inlining of IIFEs (immediately-invoked function expressions) only worked if the body contained a single return statement. Now it should also work if the body contains a single expression statement instead:

  // Original code
  const foo = () => {
   const cb = () => {
   console.log(x())
   }
   return cb()
  }
  // Old output (with --minify)
  const foo=()=>(()=>{console.log(x())})();
  // New output (with --minify)
  const foo=()=>{console.log(x())};

• The minifier now strips empty finally clauses (#​4353)

  This improvement means that finally clauses containing dead code can potentially cause the associated try statement to be removed from the output entirely in minified builds:

  // Original code
  function foo(callback) {
   if (DEBUG) stack.push(callback.name);
   try {
   callback();
   } finally {
   if (DEBUG) stack.pop();
   }
  }
  // Old output (with --minify --define:DEBUG=false)
  function foo(a){try{a()}finally{}}
  // New output (with --minify --define:DEBUG=false)
  function foo(a){a()}

• Allow tree-shaking of the Symbol constructor

  With this release, calling Symbol is now considered to be side-effect free when the argument is known to be a primitive value. This means esbuild can now tree-shake module-level symbol variables:

  // Original code
  const a = Symbol('foo')
  const b = Symbol(bar)
  // Old output (with --tree-shaking=true)
  const a = Symbol("foo");
  const b = Symbol(bar);
  // New output (with --tree-shaking=true)
  const b = Symbol(bar);

v0.27.0

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This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.26.0 or ~0.26.0. See npm's documentation about semver for more information.

• Use Uint8Array.fromBase64 if available (#​4286)

  With this release, esbuild's binary loader will now use the new Uint8Array.fromBase64 function unless it's unavailable in the configured target environment. If it's unavailable, esbuild's previous code for this will be used as a fallback. Note that this means you may now need to specify target when using this feature with Node (for example --target=node22) unless you're using Node v25+.

• Update the Go compiler from v1.23.12 to v1.25.4 (#​4208, #​4311)

  This raises the operating system requirements for running esbuild:

  • Linux: now requires a kernel version of 3.2 or later
  • macOS: now requires macOS 12 (Monterey) or later

v0.26.0

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• Enable trusted publishing (#​4281)

  GitHub and npm are recommending that maintainers for packages such as esbuild switch to trusted publishing. With this release, a VM on GitHub will now build and publish all of esbuild's packages to npm instead of me. In theory.

  Unfortunately there isn't really a way to test that this works other than to do it live. So this release is that live test. Hopefully this release is uneventful and is exactly the same as the previous one (well, except for the green provenance attestation checkmark on npm that happens with trusted publishing).