File: /var/www/myc/api-management/node_modules/@css-inline/css-inline/README.md
# css-inline
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`css-inline` is a high-performance library for inlining CSS into HTML 'style' attributes.
This library is designed for scenarios such as preparing HTML emails or embedding HTML into third-party web pages.
For instance, the library transforms HTML like this:
```html
<html>
<head>
<style>h1 { color:blue; }</style>
</head>
<body>
<h1>Big Text</h1>
</body>
</html>
```
into:
```html
<html>
<head></head>
<body>
<h1 style="color:blue;">Big Text</h1>
</body>
</html>
```
- Uses reliable components from Mozilla's Servo project
- Inlines CSS from `style` and `link` tags
- Removes `style` and `link` tags
- Resolves external stylesheets (including local files)
- Optionally caches external stylesheets
- Works on Linux, Windows, and macOS
- Supports HTML5 & CSS3
- Tested on Node.js 18 & 20.
## Playground
If you'd like to try `css-inline`, you can check the WebAssembly-powered [playground](https://css-inline.org/) to see the results instantly.
## Installation
### Node.js
Install with `npm`:
```shell
npm i @css-inline/css-inline
```
## Usage
```typescript
import { inline } from "@css-inline/css-inline";
var inlined = inline(
`
<html>
<head>
<style>h1 { color:red }</style>
</head>
<body>
<h1>Test</h1>
</body>
</html>
`,
);
// Do something with the inlined HTML, e.g. send an email
```
Note that `css-inline` automatically adds missing `html` and `body` tags, so the output is a valid HTML document.
Alternatively, you can inline CSS into an HTML fragment, preserving the original structure:
```javascript
import { inlineFragment } from "@css-inline/css-inline";
var inlined = inlineFragment(
`
<main>
<h1>Hello</h1>
<section>
<p>who am i</p>
</section>
</main>
`,
`
p {
color: red;
}
h1 {
color: blue;
}
`
);
// HTML becomes this:
// <main>
// <h1 style="color: blue;">Hello</h1>
// <section>
// <p style="color: red;">who am i</p>
// </section>
// </main>
```
### Configuration
- `inlineStyleTags`. Specifies whether to inline CSS from "style" tags. Default: `true`
- `keepStyleTags`. Specifies whether to keep "style" tags after inlining. Default: `false`
- `keepLinkTags`. Specifies whether to keep "link" tags after inlining. Default: `false`
- `baseUrl`. The base URL used to resolve relative URLs. If you'd like to load stylesheets from your filesystem, use the `file://` scheme. Default: `null`
- `loadRemoteStylesheets`. Specifies whether remote stylesheets should be loaded. Default: `true`
- `cache`. Specifies caching options for external stylesheets (for example, `{size: 5}`). Default: `null`
- `extraCss`. Extra CSS to be inlined. Default: `null`
- `preallocateNodeCapacity`. **Advanced**. Preallocates capacity for HTML nodes during parsing. This can improve performance when you have an estimate of the number of nodes in your HTML document. Default: `32`
You can also skip CSS inlining for an HTML tag by adding the `data-css-inline="ignore"` attribute to it:
```html
<head>
<style>h1 { color:blue; }</style>
</head>
<body>
<!-- The tag below won't receive additional styles -->
<h1 data-css-inline="ignore">Big Text</h1>
</body>
</html>
```
The `data-css-inline="ignore"` attribute also allows you to skip `link` and `style` tags:
```html
<head>
<!-- Styles below are ignored -->
<style data-css-inline="ignore">h1 { color:blue; }</style>
</head>
<body>
<h1>Big Text</h1>
</body>
```
Alternatively, you may keep `style` from being removed by using the `data-css-inline="keep"` attribute.
This is useful if you want to keep `@media` queries for responsive emails in separate `style` tags:
```html
<head>
<!-- Styles below are not removed -->
<style data-css-inline="keep">h1 { color:blue; }</style>
</head>
<body>
<h1>Big Text</h1>
</body>
```
Such tags will be kept in the resulting HTML even if the `keep_style_tags` option is set to `false`.
You can also cache external stylesheets to avoid excessive network requests:
```typescript
import { inline } from "@css-inline/css-inline";
var inlined = inline(
`
<html>
<head>
<link href="http://127.0.0.1:1234/external.css" rel="stylesheet">
<style>h1 { color:red }</style>
</head>
<body>
<h1>Test</h1>
</body>
</html>
`,
{ cache: { size: 5 } },
);
```
Caching is disabled by default.
## WebAssembly
`css-inline` also ships a WebAssembly module built with `wasm-bindgen` to run in browsers.
```html
<script src="https://unpkg.com/@css-inline/css-inline-wasm"></script>
<script>
// Initialize the WASM module first
cssInline.initWasm(fetch('https://unpkg.com/@css-inline/css-inline-wasm/index_bg.wasm'));
const inlinedHtml = cssInline.inline(`<html>
<head>
<style>h1 { color:blue; }</style>
</head>
<body>
<h1>Big Text</h1>
</body>
</html>`);
document.getElementById('output').src = inlinedHtml
</script>
```
**NOTE**: WASM module currently lacks support for fetching stylesheets from network or filesystem and caching.
## Performance
`css-inline` is powered by efficient tooling from Mozilla's Servo project and significantly outperforms other JavaScript alternatives in terms of speed.
Most of the time it achieves over a **3x** speed advantage compared to the next fastest alternative.
Here is the performance comparison:
| | Size | `css-inline 0.14.0` | `css-inline-wasm 0.13.0` | `juice 10.0.0` | `inline-css 4.0.2` |
|-------------|---------|---------------------|--------------------------|-----------------------|----------------------|
| Basic | 230 B | 16.82 µs | 20.92 µs (**1.24x**) | 57.00 µs (**3.38x**) | 68.43 µs (**4.06x**) |
| Realistic-1 | 8.58 KB | 351.74 µs | 452.28 µs (**1.28x**) | 859.10 µs (**2.44x**) | 1.04 ms (**2.98x**) |
| Realistic-2 | 4.3 KB | 203.25 µs | 269.54 µs (**1.32x**) | 1.02 ms (**5.04x**) | 861.32 µs (**4.23x**) |
The "Basic" case was obtained from benchmarking the example from the Usage section.
The benchmarking code is available in the `benches/bench.ts` file. The benchmarks were conducted using the stable `rustc 1.77.1` on Node.js `v21.1.0`.
## License
This project is licensed under the terms of the [MIT license](https://opensource.org/licenses/MIT).