Fix a regression with baseURL in tsconfig.json (#3307)

The previous release moved tsconfig.json path resolution before --packages=external checks to allow the paths field in tsconfig.json to avoid a package being marked as external. However, that reordering accidentally broke the behavior of the baseURL field from tsconfig.json. This release moves these path resolution rules around again in an attempt to allow both of these cases to work.

Parse TypeScript type arguments for JavaScript decorators (#3308)

When parsing JavaScript decorators in TypeScript (i.e. with experimentalDecorators disabled), esbuild previously didn't parse type arguments. Type arguments will now be parsed starting with this release. For example:

@foo<number>
@bar<number, string>()
class Foo {}

Fix glob patterns matching extra stuff at the end (#3306)

Previously glob patterns such as ./*.js would incorrectly behave like ./*.js* during path matching (also matching .js.map files, for example). This was never intentional behavior, and has now been fixed.

Change the permissions of esbuild's generated output files (#3285)

This release changes the permissions of the output files that esbuild generates to align with the default behavior of node's fs.writeFileSync function. Since most tools written in JavaScript use fs.writeFileSync, this should make esbuild more consistent with how other JavaScript build tools behave.

The full Unix-y details: Unix permissions use three-digit octal notation where the three digits mean "user, group, other" in that order. Within a digit, 4 means "read" and 2 means "write" and 1 means "execute". So 6 == 4 + 2 == read + write. Previously esbuild uses 0644 permissions (the leading 0 means octal notation) but the permissions for fs.writeFileSync defaults to 0666, so esbuild will now use 0666 permissions. This does not necessarily mean that the files esbuild generates will end up having 0666 permissions, however, as there is another Unix feature called "umask" where the operating system masks out some of these bits. If your umask is set to 0022 then the generated files will have 0644 permissions, and if your umask is set to 0002 then the generated files will have 0664 permissions.

Fix a subtle CSS ordering issue with @import and @layer

With this release, esbuild may now introduce additional @layer rules when bundling CSS to better preserve the layer ordering of the input code. Here's an example of an edge case where this matters:

/* entry.css */
@import "a.css";
@import "b.css";
@import "a.css";

/* a.css */
@layer a {
  body {
    background: red;
  }
}

/* b.css */
@layer b {
  body {
    background: green;
  }
}

This CSS should set the body background to green, which is what happens in the browser. Previously esbuild generated the following output which incorrectly sets the body background to red:

/* b.css */
@layer b {
  body {
    background: green;
  }
}

/* a.css */
@layer a {
  body {
    background: red;
  }
}

This difference in behavior is because the browser evaluates a.css + b.css + a.css (in CSS, each @import is replaced with a copy of the imported file) while esbuild was only writing out b.css + a.css. The first copy of a.css wasn't being written out by esbuild for two reasons: 1) bundlers care about code size and try to avoid emitting duplicate CSS and 2) when there are multiple copies of a CSS file, normally only the last copy matters since the last declaration with equal specificity wins in CSS.

However, @layer was recently added to CSS and for @layer the first copy matters because layers are ordered using their first location in source code order. This introduction of @layer means esbuild needs to change its bundling algorithm. An easy solution would be for esbuild to write out a.css twice, but that would be inefficient. So what I'm going to try to have esbuild do with this release is to write out an abbreviated form of the first copy of a CSS file that only includes the @layer information, and then still only write out the full CSS file once for the last copy. So esbuild's output for this edge case now looks like this:

/* a.css */
@layer a;

/* b.css */
@layer b {
  body {
    background: green;
  }
}

/* a.css */
@layer a {
  body {
    background: red;
  }
}

The behavior of the bundled CSS now matches the behavior of the unbundled CSS. You may be wondering why esbuild doesn't just write out a.css first followed by b.css. That would work in this case but it doesn't work in general because for any rules outside of a @layer rule, the last copy should still win instead of the first copy.

Fix a bug with esbuild's TypeScript type definitions (#3299)

This release fixes a copy/paste error with the TypeScript type definitions for esbuild's JS API:

 export interface TsconfigRaw {
   compilerOptions?: {
-    baseUrl?: boolean
+    baseUrl?: string
     ...
   }
 }

This fix was contributed by @privatenumber.

Fix a regression with whitespace inside :is() (#3265)

The change to parse the contents of :is() in version 0.18.14 introduced a regression that incorrectly flagged the contents as a syntax error if the contents started with a whitespace token (for example div:is( .foo ) {}). This regression has been fixed.

Add the --serve-fallback= option (#2904)

The web server built into esbuild serves the latest in-memory results of the configured build. If the requested path doesn't match any in-memory build result, esbuild also provides the --servedir= option to tell esbuild to serve the requested path from that directory instead. And if the requested path doesn't match either of those things, esbuild will either automatically generate a directory listing (for directories) or return a 404 error.

Starting with this release, that last step can now be replaced with telling esbuild to serve a specific HTML file using the --serve-fallback= option. This can be used to provide a "not found" page for missing URLs. It can also be used to implement a single-page app that mutates the current URL and therefore requires the single app entry point to be served when the page is loaded regardless of whatever the current URL is.

Use the tsconfig field in package.json during extends resolution (#3247)

This release adds a feature from TypeScript 3.2 where if a tsconfig.json file specifies a package name in the extends field and that package's package.json file has a tsconfig field, the contents of that field are used in the search for the base tsconfig.json file.

Implement CSS nesting without :is() when possible (#1945)

Previously esbuild would always produce a warning when transforming nested CSS for a browser that doesn't support the :is() pseudo-class. This was because the nesting transform needs to generate an :is() in some complex cases which means the transformed CSS would then not work in that browser. However, the CSS nesting transform can often be done without generating an :is(). So with this release, esbuild will no longer warn when targeting browsers that don't support :is() in the cases where an :is() isn't needed to represent the nested CSS.

In addition, esbuild's nested CSS transform has been updated to avoid generating an :is() in cases where an :is() is preferable but there's a longer alternative that is also equivalent. This update means esbuild can now generate a combinatorial explosion of CSS for complex CSS nesting syntax when targeting browsers that don't support :is(). This combinatorial explosion is necessary to accurately represent the original semantics. For example:

/* Original code */
.first,
.second,
.third {
  & > & {
    color: red;
  }
}

/* Old output (with --target=chrome80) */
:is(.first, .second, .third) > :is(.first, .second, .third) {
  color: red;
}

/* New output (with --target=chrome80) */
.first > .first,
.first > .second,
.first > .third,
.second > .first,
.second > .second,
.second > .third,
.third > .first,
.third > .second,
.third > .third {
  color: red;
}

This change means you can now use CSS nesting with esbuild when targeting an older browser that doesn't support :is(). You'll now only get a warning from esbuild if you use complex CSS nesting syntax that esbuild can't represent in that older browser without using :is(). There are two such cases:

/* Case 1 */
a b {
  .foo & {
    color: red;
  }
}

/* Case 2 */
a {
  > b& {
    color: red;
  }
}

These two cases still need to use :is(), both for different reasons, and cannot be used when targeting an older browser that doesn't support :is():

/* Case 1 */
.foo :is(a b) {
  color: red;
}

/* Case 2 */
a > a:is(b) {
  color: red;
}

Automatically lower inset in CSS for older browsers

With this release, esbuild will now automatically expand the inset property to the top, right, bottom, and left properties when esbuild's target is set to a browser that doesn't support inset:

/* Original code */
.app {
  position: absolute;
  inset: 10px 20px;
}

/* Old output (with --target=chrome80) */
.app {
  position: absolute;
  inset: 10px 20px;
}

/* New output (with --target=chrome80) */
.app {
  position: absolute;
  top: 10px;
  right: 20px;
  bottom: 10px;
  left: 20px;
}

Add support for the new @starting-style CSS rule (#3249)

This at rule allow authors to start CSS transitions on first style update. That is, you can now make the transition take effect when the display property changes from none to block.

/* Original code */
@starting-style {
  h1 {
    background-color: transparent;
  }
}

/* Output */
@starting-style{h1{background-color:transparent}}

This was contributed by @yisibl.