evanw/esbuild v0.14.43

on GitHub

Fix TypeScript parse error whe a generic function is the first type argument (#2306)

In TypeScript, the << token may need to be split apart into two < tokens if it's present in a type argument context. This was already correctly handled for all type expressions and for identifier expressions such as in the following code:

// These cases already worked in the previous release
let foo: Array<<T>() => T>;
bar<<T>() => T>;

However, normal expressions of the following form were previously incorrectly treated as syntax errors:

// These cases were broken but have now been fixed
foo.bar<<T>() => T>;
foo?.<<T>() => T>();

With this release, these cases now parsed correctly.

Fix minification regression with pure IIFEs (#2279)

An Immediately Invoked Function Expression (IIFE) is a function call to an anonymous function, and is a way of introducing a new function-level scope in JavaScript since JavaScript lacks a way to do this otherwise. And a pure function call is a function call with the special /* @__PURE__ */ comment before it, which tells JavaScript build tools that the function call can be considered to have no side effects (and can be removed if it's unused).

Version 0.14.9 of esbuild introduced a regression that changed esbuild's behavior when these two features were combined. If the IIFE body contains a single expression, the resulting output still contained that expression instead of being empty. This is a minor regression because you normally wouldn't write code like this, so this shouldn't come up in practice, and it doesn't cause any correctness issues (just larger-than-necessary output). It's unusual that you would tell esbuild "remove this if the result is unused" and then not store the result anywhere, since the result is unused by construction. But regardless, the issue has now been fixed.

For example, the following code is a pure IIFE, which means it should be completely removed when minification is enabled. Previously it was replaced by the contents of the IIFE but it's now completely removed:

// Original code
/* @__PURE__ */ (() => console.log(1))()

// Old output (with --minify)
console.log(1);

// New output (with --minify)

Add log messages for indirect require references (#2231)

A long time ago esbuild used to warn about indirect uses of require because they break esbuild's ability to analyze the dependencies of the code and cause dependencies to not be bundled, resulting in a potentially broken bundle. However, this warning was removed because many people wanted the warning to be removed. Some packages have code that uses require like this but on a code path that isn't used at run-time, so their code still happens to work even though the bundle is incomplete. For example, the following code will not bundle bindings:

// Prevent React Native packager from seeing modules required with this
const nodeRequire = require;

function getRealmConstructor(environment) {
  switch (environment) {
    case "node.js":
    case "electron":
      return nodeRequire("bindings")("realm.node").Realm;
  }
}

Version 0.11.11 of esbuild removed this warning, which means people no longer have a way to know at compile time whether their bundle is broken in this way. Now that esbuild has custom log message levels, this warning can be added back in a way that should make both people happy. With this release, there is now a log message for this that defaults to the debug log level, which normally isn't visible. You can either do --log-override:indirect-require=warning to make this log message a warning (and therefore visible) or use --log-level=debug to see this and all other debug log messages.