esbuild 0.12.19

v0.12.19

on Node.js NPM

Add support for CSS source maps (#519)

With this release, esbuild will now generate source maps for CSS output files when --sourcemap is enabled. This supports all of the same options as JS source maps including --sourcemap=inline and --sourcemap=external. In addition, CSS input files with embedded /*# sourceMappingURL=... */ comments will cause the CSS output file source map to map all the way back to the original inputs. CSS source maps are used by the browser's style inspector to link back to the original source code instead of linking to the bundled source code.

Fix computed class fields in TypeScript edge case (#1507)

If TypeScript code contains computed class fields, the target environment supports class fields so syntax lowering is not necessary, and TypeScript's useDefineForClassFields setting is set to true, then esbuild had a bug where the computed property names were computed after the class definition and were undefined. Note that TypeScript's useDefineForClassFields setting defaults to true if tsconfig.json contains "target": "ESNext".

// Original code
class Foo {
  [foo] = 1;
  @bar [baz] = 2;
}

// Old output
var _a, _b;
var Foo = class {
  [_a] = 1;
  [_b] = 2;
};
_a = foo, _b = baz;
__decorateClass([
  bar
], Foo.prototype, _b, 2);

// New output
var _a;
var Foo = class {
  [foo] = 1;
  [_a = baz] = 2;
};
__decorateClass([
  bar
], Foo.prototype, _a, 2);

The problem in this case is that normally TypeScript moves class field initializers into the special constructor method (automatically generating one if one doesn't already exist) so the side effects for class field property names must happen after the class body. But if class fields are supported by the target environment then the side effects must happen inline instead.