All JavaScript stemmers have been transpiled from Java implementation of Snowball stemming algorithms using ESJava transpiler.

This project provides not only pre-built JavaScript stemmers, but allows to create new ones.

Stemmers for 20+ languages are packed in one file in two ECMAScript standards:

• ES6
• ES5

You can test stemmers directly in online demo.

As there are several limitations of ESJava transpiler, the build process has to be complemented by pre- and post-transpiling tweaks.

• Unix-like OS (or Cygwin on Windows)
• Node.js + npm
• rsync (for syncing Snowball repository, required only in specific scenarios)
• perl (for generating Java code from Snowball algorithms (SBL files), required only in specific scenarios)

1. Building Java stemmers from most recent Snowball stemmers
2. Creating a Java bundle
3. Tweaking the Java bundle
4. Transpiling the Java bundle to JavaScript
5. Modifying the transpiled JavaScript

1. Building Java stemmers from most recent Snowball stemmers
2. Building Java stemmers from custom Snowball stemmers
3. Creating a Java bundle
4. Adding custom Java stemmers into the bundle
5. Tweaking the Java bundle
6. Transpiling the Java bundle to JavaScript
7. Modifying the transpiled JavaScript

git clone https://github.com/mazko/jssnowball.git
cd jssnowball/
make bundle

1. Change directory to jssnoball/snowball-master/
2. Create new subfolder in the algorithms folder and copy there the given SBL file renamed to stem_Unicode.sbl
3. Add stemmer configuration into libstemmer/modules.txt and libstemmer/modules_utf8.txt
4. Add stemmer to the GNUmakefile's libstemmer_algorithms variable
5. Compile the Snowball using make dist

As ESJava can convert a single file only, all Java source files have to be bundled first.

git checkout -- js_snowball/eclipse/
make bundle

Copy the Java stemmer code from jssnoball/snowball-master/java/org/tartarus/snowball/ext/ into jssnowball/js_snowball/lib/snowball.bundle.java.

It also recommended to remove unused code like copy_from, hashCode etc. Here is Eclipse EE Mars.1 Release (4.5.1) example:

source -> cleanup

There are some Java constructions that can't be translated to JavaScipt directly, e.g. reflection etc. Such fragments has to be tweaked a bit.

Fortunately, most of them are in the common code, not in stemmers themselves (except for finnishStemmer). They are wrapped inside :es6: code :end: and should be edited as suggested in comments.

On top of that, these further tweaks are required:

• removing package names in method references (org.tartarus.snowball, java.lang)
• removing some overloaded methods

The result should match the original snowball.bundle.java file.

npm i -g esjava babel-cli
npm i babel-preset-es2015 babel-plugin-transform-es2015-modules-umd
make esjava

In the final JavaScript files (stored in jssnowball/js_snowball/lib/ directory) it is necessary to replace s.length() with s.length in eq_s and eq_s_b methods. Otherwise the code returns a TypeError: s.length is not a function.