rollup-plugin-hamber v5.0.3
rollup-plugin-hamber
Compile Hamber components.
Installation
npm install --save-dev hamber rollup-plugin-hamber
Note that we need to install Hamber as well as the plugin, as it's a 'peer dependency'.
Usage
// rollup.config.js
import * as fs from 'fs';
import hamber from 'rollup-plugin-hamber';
export default {
input: 'src/main.js',
output: {
file: 'public/bundle.js',
format: 'iife'
},
plugins: [
hamber({
// By default, all .hamber and .html files are compiled
extensions: ['.my-custom-extension'],
// You can restrict which files are compiled
// using `include` and `exclude`
include: 'src/components/**/*.hamber',
// By default, the client-side compiler is used. You
// can also use the server-side rendering compiler
generate: 'ssr',
// Optionally, preprocess components with hamber.preprocess:
// https://github.com/hamberjs/hamber#preprocessor-options
preprocess: {
style: ({ content }) => {
return transformStyles(content);
}
},
// Emit CSS as "files" for other plugins to process
emitCss: true,
// Extract CSS into a separate file (recommended).
// See note below
css: function (css) {
console.log(css.code); // the concatenated CSS
console.log(css.map); // a sourcemap
// creates `main.css` and `main.css.map` — pass `false`
// as the second argument if you don't want the sourcemap
css.write('public/main.css');
},
// Warnings are normally passed straight to Rollup. You can
// optionally handle them here, for example to squelch
// warnings with a particular code
onwarn: (warning, handler) => {
// e.g. don't warn on <marquee> elements, cos they're cool
if (warning.code === 'a11y-distracting-elements') return;
// let Rollup handle all other warnings normally
handler(warning);
}
})
]
}
Preprocessing and dependencies
If you are using the preprocess
feature, then your callback responses may — in addition to the code
and map
values described in the Hamber compile docs — also optionally include a dependencies
array. This should be the paths of additional files that the preprocessor result in some way depends upon. In Rollup 0.61+ in watch mode, any changes to these additional files will also trigger re-builds.
pkg.hamber
If you're importing a component from your node_modules folder, and that component's package.json has a "hamber"
property...
{
"name": "some-component",
// this means 'some-component' resolves to 'some-component/src/SomeComponent.hamber'
"hamber": "src/MyComponent.hamber"
}
...then this plugin will ensure that your app imports the uncompiled component source code. That will result in a smaller, faster app (because code is deduplicated, and shared functions get optimized quicker), and makes it less likely that you'll run into bugs caused by your app using a different version of Hamber to the component.
Conversely, if you're publishing a component to npm, you should ship the uncompiled source (together with the compiled distributable, for people who aren't using Hamber elsewhere in their app) and include the "hamber"
property in your package.json.
Extracting CSS
If your Hamber components contain <style>
tags, by default the compiler will add JavaScript that injects those styles into the page when the component is rendered. That's not ideal, because it adds weight to your JavaScript, prevents styles from being fetched in parallel with your code, and can even cause CSP violations.
A better option is to extract the CSS into a separate file. Using the css
option as shown above would cause a public/main.css
file to be generated each time the bundle is built (or rebuilt, if you're using rollup-watch), with the normal scoping rules applied.
If you have other plugins processing your CSS (e.g. rollup-plugin-scss), and want your styles passed through to them to be bundled together, you can use emitCss: true
.
Alternatively, if you're handling styles in some other way and just want to prevent the CSS being added to your JavaScript bundle, use css: false
.
License
MIT