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@github-actions github-actions released this 19 Nov 07:12
v0.19.6
6073a3a

  • Fix a constant folding bug with bigint equality

    This release fixes a bug where esbuild incorrectly checked for bigint equality by checking the equality of the bigint literal text. This is correct if the bigint doesn't have a radix because bigint literals without a radix are always in canonical form (since leading zeros are not allowed). However, this is incorrect if the bigint has a radix (e.g. 0x123n) because the canonical form is not enforced when a radix is present.

    // Original code
console.log(!!0n, !!1n, 123n === 123n)
console.log(!!0x0n, !!0x1n, 123n === 0x7Bn)

// Old output
console.log(false, true, true);
console.log(true, true, false);

// New output
console.log(false, true, true);
console.log(!!0x0n, !!0x1n, 123n === 0x7Bn);

  • Add some improvements to the JavaScript minifier

    This release adds more cases to the JavaScript minifier, including support for inlining String.fromCharCode and String.prototype.charCodeAt when possible:

    // Original code
document.onkeydown = e => e.keyCode === 'A'.charCodeAt(0) && console.log(String.fromCharCode(55358, 56768))

// Old output (with --minify)
document.onkeydown=o=>o.keyCode==="A".charCodeAt(0)&&console.log(String.fromCharCode(55358,56768));

// New output (with --minify)
document.onkeydown=o=>o.keyCode===65&&console.log("🧀");

    In addition, immediately-invoked function expressions (IIFEs) that return a single expression are now inlined when minifying. This makes it possible to use IIFEs in combination with @__PURE__ annotations to annotate arbitrary expressions as side-effect free without the IIFE wrapper impacting code size. For example:

    // Original code
const sideEffectFreeOffset = /* @__PURE__ */ (() => computeSomething())()
use(sideEffectFreeOffset)

// Old output (with --minify)
const e=(()=>computeSomething())();use(e);

// New output (with --minify)
const e=computeSomething();use(e);

  • Automatically prefix the mask-composite CSS property for WebKit (#3493)

    The mask-composite property will now be prefixed as -webkit-mask-composite for older WebKit-based browsers. In addition to prefixing the property name, handling older browsers also requires rewriting the values since WebKit uses non-standard names for the mask composite modes:

    /* Original code */
div {
  mask-composite: add, subtract, intersect, exclude;
}

/* New output (with --target=chrome100) */
div {
  -webkit-mask-composite:
    source-over,
    source-out,
    source-in,
    xor;
  mask-composite:
    add,
    subtract,
    intersect,
    exclude;
}

  • Avoid referencing this from JSX elements in derived class constructors (#3454)

    When you enable --jsx=automatic and --jsx-dev, the JSX transform is supposed to insert this as the last argument to the jsxDEV function. I'm not sure exactly why this is and I can't find any specification for it, but in any case this causes the generated code to crash when you use a JSX element in a derived class constructor before the call to super() as this is not allowed to be accessed at that point. For example

    // Original code
class ChildComponent extends ParentComponent {
  constructor() {
    super(<div />)
  }
}

// Problematic output (with --loader=jsx --jsx=automatic --jsx-dev)
import { jsxDEV } from "react/jsx-dev-runtime";
class ChildComponent extends ParentComponent {
  constructor() {
    super(/* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
      fileName: "<stdin>",
      lineNumber: 3,
      columnNumber: 15
    }, this)); // The reference to "this" crashes here
  }
}

    The TypeScript compiler doesn't handle this at all while the Babel compiler just omits this for the entire constructor (even after the call to super()). There seems to be no specification so I can't be sure that this change doesn't break anything important. But given that Babel is pretty loose with this and TypeScript doesn't handle this at all, I'm guessing this value isn't too important. React's blog post seems to indicate that this value was intended to be used for a React-specific migration warning at some point, so it could even be that this value is irrelevant now. Anyway the crash in this case should now be fixed.

  • Allow package subpath imports to map to node built-ins (#3485)

    You are now able to use a subpath import in your package to resolve to a node built-in module. For example, with a package.json file like this:

    {
  "type": "module",
  "imports": {
    "#stream": {
      "node": "stream",
      "default": "./stub.js"
    }
  }
}

    You can now import from node's stream module like this:

    import * as stream from '#stream';
console.log(Object.keys(stream));

    This will import from node's stream module when the platform is node and from ./stub.js otherwise.

  • No longer throw an error when a Symbol is missing (#3453)

    Certain JavaScript syntax features use special properties on the global Symbol object. For example, the asynchronous iteration syntax uses Symbol.asyncIterator. Previously esbuild's generated code for older browsers required this symbol to be polyfilled. However, starting with this release esbuild will use Symbol.for() to construct these symbols if they are missing instead of throwing an error about a missing polyfill. This means your code no longer needs to include a polyfill for missing symbols as long as your code also uses Symbol.for() for missing symbols.

  • Parse upcoming changes to TypeScript syntax (#3490, #3491)

    With this release, you can now use from as the name of a default type-only import in TypeScript code, as well as of as the name of an await using loop iteration variable:

    import type from from 'from'
for (await using of of of) ;

    This matches similar changes in the TypeScript compiler (#56376 and #55555) which will start allowing this syntax in an upcoming version of TypeScript. Please never actually write code like this.

    The type-only import syntax change was contributed by @magic-akari.

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