js: Support JSX and JSXImportSourceOptions

Fixes #12118

content/en/functions/js/Build.md

@@ -111,6 +111,29 @@ format
 sourceMap
 : (`string`) Whether to generate `inline` or `external` source maps from esbuild. External source maps will be written to the target with the output file name + ".map". Input source maps can be read from js.Build and node modules and combined into the output source maps. By default, source maps are not created.
 
+JSX {{< new-in 0.124.0 >}}
+: (`string`) How to handle/transform JSX syntax. One of: `transform`, `preserve`, `automatic`. Default is `transform`. Notably, the `automatic` transform was introduced in React 17+ and will cause the necessary JSX helper functions to be imported automatically. See https://esbuild.github.io/api/#jsx
+
+JSXImportSource {{< new-in 0.124.0 >}}
+: (`string`) Which library to use to automatically import its JSX helper functions from. This only works if `JSX` is set to `automatic`. The specified library needs to be installed through NPM and expose certain exports. See https://esbuild.github.io/api/#jsx-import-source
+
+The combination of `JSX` and `JSXImportSource` is helpful if you want to use a non-React JSX library like Preact, e.g.:
+
+```go-html-template
+{{ $js := resources.Get "js/main.jsx" | js.Build (dict "JSX" "automatic" "JSXImportSource" "preact") }}
+```
+
+With the above, you can use Preact components and JSX without having to manually import `h` and `Fragment` every time:
+
+```jsx
+import { render } from 'preact';
+
+const App = () => <>Hello world!</>;
+
+const container = document.getElementById('app');
+if (container) render(<App />, container);
+```
+
 ### Import JS code from /assets
 
 `js.Build` has full support for the virtual union file system in [Hugo Modules](/hugo-modules/). You can see some simple examples in this [test project](https://github.com/gohugoio/hugoTestProjectJSModImports), but in short this means that you can do this:

content/en/hugo-pipes/js.md

@@ -95,6 +95,29 @@ format
 sourceMap
 : (`string`) Whether to generate `inline` or `external` source maps from esbuild. External source maps will be written to the target with the output file name + ".map". Input source maps can be read from js.Build and node modules and combined into the output source maps. By default, source maps are not created.
 
+JSX {{< new-in 0.124.0 >}}
+: (`string`) How to handle/transform JSX syntax. One of: `transform`, `preserve`, `automatic`. Default is `transform`. Notably, the `automatic` transform was introduced in React 17+ and will cause the necessary JSX helper functions to be imported automatically. See https://esbuild.github.io/api/#jsx
+
+JSXImportSource {{< new-in 0.124.0 >}}
+: (`string`) Which library to use to automatically import its JSX helper functions from. This only works if `JSX` is set to `automatic`. The specified library needs to be installed through NPM and expose certain exports. See https://esbuild.github.io/api/#jsx-import-source
+
+The combination of `JSX` and `JSXImportSource` is helpful if you want to use a non-React JSX library like Preact, e.g.:
+
+```go-html-template
+{{ $js := resources.Get "js/main.jsx" | js.Build (dict "JSX" "automatic" "JSXImportSource" "preact") }}
+```
+
+With the above, you can use Preact components and JSX without having to manually import `h` and `Fragment` every time:
+
+```jsx
+import { render } from 'preact';
+
+const App = () => <>Hello world!</>;
+
+const container = document.getElementById('app');
+if (container) render(<App />, container);
+```
+
 ### Import JS code from /assets
 
 `js.Build` has full support for the virtual union file system in [Hugo Modules](/hugo-modules/). You can see some simple examples in this [test project](https://github.com/gohugoio/hugoTestProjectJSModImports), but in short this means that you can do this: