Fork of https://www.npmjs.com/package/xmllint with some updates
npm install xmllint-wasmlibxml2's xmllint tool compiled to WebAssembly using Emscripten, to be used
in Node.js applications in environments where you can't or don't want to
depend on the native library.
This is a fork of Alan Zakai's amazing work at
kripken/xml.js
(be sure to also check out his blog post about
that exact project).
This fork continues the original build with some neat updates
as well as somewhat opinionated breaking changes.
Currently, the library only works in Node.js, but browser support could be
added if there's a demand for it. I'll probably stick to wasm builds only in
this repository, though, so if you need an asm.js build for browsers that
don't yet support wasm, you should probably go with the original project
instead.
* libxml2 version is upgraded to v2.13.8
* The output is wasm instead of asm.js
* In addition to modern browsers with wasm support, works in Node.js 12 or later
* Library size is quite a bit smaller, the wasm file and wrapper js files
weigh about 860K combined
* Allows normalization / formatting of the input XML in addition to validation
* There are some changes to the API, which is described in more detail
below. Overall this project behaves more like a library that you'd call from
a JS application, instead of like a command-line tool that xmllint normally is.
sh
npm i xmllint-wasm
`
The library uses Node.js Worker threads
to isolate the Emscripten wrapper from your main process (so that
when it calls process.exit your whole server won't go down).
We require Node.js version 16 or later.API
See type definitions at index.d.ts.
$3
javascript
const {validateXML, memoryPages} = require('xmllint-wasm');async function example() {
const [myXMLFile, mySchemaFile, generalXmlXsdFile] = await Promise.all([
fs.promises.readFile('./my-xml-file.xml', 'utf8'),
fs.promises.readFile('./my-schema-file.xsd', 'utf8'),
// Some other XSD file that our main schema my-schema-file.xsd happens to depend on
fs.promises.readFile('./xml.xsd', 'utf8'),
])
const validationResult = await validateXML({
xml: [{
fileName: 'my-xml-file.xml',
contents: myXMLFile,
}],
// All the schema files that are required to validate the documents.
// The main XSD should be first in the array, followed by its possible dependencies.
schema: [mySchemaFile],
// Optional: Files that the schema file depends on (xsd:import, xsd:include).
// xmllint-wasm won't make any network requests or other IO to retrieve depdencicy files,
// so these they must be loaded beforehand and passed in here.
preload: [{
fileName: 'xml.xsd',
contents: generalXmlXsdFile,
}],
// Optional: Initial memory capacity in Web Assembly memory pages (1 = 6.4KiB) - 256
// is minimum and default here (16MiB).
initialMemoryPages: 256,
// Optional: Maximum memory capacity, in Web Assembly memory pages. If not
// set, this will also default to 256 pages. Max is 65536 (4GiB).
// Use this to raise the memory limit if your XML to validate are large enough to
// cause out of memory errors.
// The following example would set the max memory to 2GiB.
maxMemoryPages: 2 * memoryPages.GiB,
});
if (validationResult.valid) {
console.log('There were no errors!')
} else {
console.warn(validationResult.errors);
}
}
`
Giving explicit fileNames is optional (you can just pass the file contents
as string instead), but might help with mapping the correct error to a correct
file if you are validating multiple files at once. If you want the output to contain the (formatted) input XML, add
or normalization: 'c14n' to the options.The return value is a Promise. Even though the xmllint command-line tool
returns with a non-zero exit code if the xml fails to validate, we
don't reject the Promise if there are validation errors as long as
the validation completes successfully. Unexpected errors, like
a syntax error in schema file, do reject the Promise.
The Promise resolved with a object like the following
`javascript{
valid: false,
errors: [
{
// Raw output from running xmllint for
// this particular error/line of the output
rawMessage: "my-xml-file.xml:21: element quantity: Schemas validity error : Element 'quantity': [facet 'maxExclusive'] The value '1000' must be less than '100'.",
// Error message without the location info
message: "element quantity: Schemas validity error : Element 'quantity': [facet 'maxExclusive'] The value '1000' must be less than '100'.",
// Error location info, if we managed to parse that from the output (null otherwise)
loc: { fileName: 'my-xml-file.xml', lineNumber: 21 }
}
],
// Raw output string from running xmllint
rawOutput: "my-xml-file.xml:21: element quantity: Schemas validity error ...",
normalized: ""
}
`$3
Check ./browser-demo/html-data index.html and
logic.js for a full example. Import the browser version, index-browser.js, as an
EcmaScript module and use like you would use the Node.js version.
Works out of the box in latest Chrome, Edge and Safari.
Firefox, however, does not support Worker modules yet (tracked in issue
1247687), which would be
required by the implementation in this library.
To get Firefox to work, you'll need to use a bundler like Parcel or
Webpack to bundle the sources from modules to regular old scripts.
javascript
import * as xmllint from './node_modules/xmllint/index-browser.mjs';
`Building xmllint from source
Clone the project (including the submodules with git
) and build. $3
`sh
npm run build
`$3
Install emscripten
and source their shell env.
Finally, run the commands for Emscripten build
sh
./script/clean
./script/libxml2
./script/compile
./script/test
``