Vulcanize
Concatenate a set of Web Components into one file
Named for the Vulcanization process that turns polymers into more durable materials.
Installation
vulcanize is available on npm. For maximium utility, vulcanize should be installed globally.
sudo npm install -g vulcanize
This will install vulcanize to /usr/local/bin/vulcanize.
Usage
vulcanize index.html
At the simplest, vulcanize only requires an html file as an argument. The optimized output file will be named
vulcanized.html.
If you want to control the output name, use the -o flag
vulcanize -o build.html index.html
Most URLs will be automatically adjusted by the vulcanizer.
Options
--output,-o- Output file name (defaults to vulcanized.html)
--verbose,-v- More verbose logging
--help,-v,-?- Print this message
--config- Read a given config file
--strip,-s- Remove comments and empty text nodes
--csp- Extract inline scripts to a separate file (uses
<output file name>.js) --inline- The opposite of CSP mode, inline all assets (script and css) into the document
--inline --csp- Bundle all javascript (inline and external) into
<output file name>.js
- Bundle all javascript (inline and external) into
Config
JSON file for additional options
- Excludes: Exclude the selected urls from vulcanization (urls are still deduplicated for imports).
Example Config
{
"excludes": {
"imports": [
"regex-to-exclude"
]
}
}Example Usage
Say we have three html files: index.html, x-app.html, and x-dep.html.
index.html:
<!DOCTYPE html>
<link rel="import" href="x-app.html">
<x-app></x-app>x-app.html:
<link rel="import" href="path/to/x-dep.html">
<polymer-element name="x-app">
<template>
<x-dep></x-dep>
</template>
<script>Polymer('x-app')</script>
</polymer-element>x-dep.html:
<polymer-element name="x-dep">
<template>
<img src="x-dep-icon.jpg">
</template>
<script>
Polymer('x-dep');
</script>
</polymer-element>Running vulcan on index.html, and specifying build.html as the output:
vulcanize -o build.html index.html
Will result in build.html that appears as so:
<!DOCTYPE html>
<div hidden><polymer-element name="x-dep" assetpath="path/to/">
<template>
<img src="http://www.polymer-project.org/images/logos/p-logo.svg">
</template>
<script>
Polymer('x-dep');
</script>
</polymer-element>
<polymer-element name="x-app" assetpath="">
<template>
<x-dep></x-dep>
</template>
<script>Polymer('x-app')</script>
</polymer-element>
</div>
<x-app></x-app>Content Security Policy
Content Security Policy, or CSP, is a Javascript security model that aims to prevent XSS and other attacks. In so doing, it prohibits the use of inline scripts.
To help automate the use of Polymer element registration with CSP, the --csp flag to vulcan will remove all scripts
from the HTML Imports and place their contents into an output javascript file.
Using the previous example, the output from vulcanize --csp -o build.html index.html will be
build.html:
<!DOCTYPE html>
<div hidden><polymer-element name="x-dep" assetpath="path/to/">
<template>
<img src="http://www.polymer-project.org/images/logos/p-logo.svg">
</template>
</polymer-element>
<polymer-element name="x-app" assetpath="">
<template>
<x-dep></x-dep>
</template>
</polymer-element>
</div>
<x-app></x-app>
<script src="build.js"></script>build.js:
Polymer('x-dep');
;
Polymer('x-app')The JS files can become a bit messy without reformatting, and semi-colons are inserted between script contents as a precaution.
Stripping whitespace
Vulcanize includes a set of size reducing heuristics to remove unnecessary whitespace and comments in HTML, JS, and CSS.
This can be activated by using the --strip option.
Using the previous example, the output from vulcanize --csp -o build.html --strip index.html will be
build.html:
<!DOCTYPE html>
<div hidden><polymer-element name="x-dep" assetpath="path/to/"><template><img src="http://www.polymer-project.org/images/logos/p-logo.svg"></template></polymer-element><polymer-element name="x-app" assetpath=""><template><x-dep></x-dep></template></polymer-element></div>
<x-app></x-app>
<script src="build.js"></script>Polymer("x-dep");Polymer("x-app");
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