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    spellchecker-wasm
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    0.3.3¬†‚Äʬ†Public¬†‚Äʬ†Published

    Spellchecker + WebAssembly

    When you absolutely, positively have to have the fastest spellchecker in the room, accept no substitutes.

    Build Status Coverage Status

    • Fast - Based on SymSpell v6.6 with bigram support.
    • Plug and play - Ready to go out of the box (batteries included).

    Spellcheck-wasm is an extremely fast spellchecker for WebAssembly complete with tooling for leveraging Worker threads to guarantee lightning fast processing of a single word or very large documents without the use of native Node plugins. Sub-millisecond benchmarks bring near native speeds to spellchecking in Node.

    Spellcheck-wasm uses a zero dependency Rust port of the extremely popular SymSpell engine with several optimizations for WebAssembly.

    Electron ‚úď
    Node ‚úď
    Browsers ‚úď
    Workers ‚úď
    Cli ‚úď

    Installation

    npm i -s spellchecker-wasm

    As an interactive CLI

    npm i -g spellchecker-wasm

    Then use spellcheck to enter interactive mode. For supported arguments, run spellcheck --help.

    Usage in Electron

    // Within the preload script of your BrowserWindow instance
    const { webFrame } = require('electron');
    const { SpellcheckerWasm }  = require('spellchecker-wasm');
     
    const wasmPath = require.resolve('spellchecker-wasm/lib/spellcheck-wasm.wasm');
    const dictionaryLocation = require.resolve('spellchecker-wasm/lib/frequency_dictionary_en_82_765.txt');
    const spellchecker = new SpellcheckerWasm();
     
    spellchecker.prepareSpellchecker(wasmPath, dictionaryLocation)
        .then(() => {
            let suggestions;
            spellchecker.resultsHandler = results => {
                suggestions = results;
            };
     
            webFrame.setSpellCheckProvider('en-US', {
                spellCheck(words, callback) {
                    const misspelledWords = [];
                    words.forEach(word => {
                        spellchecker.checkSpelling(word); // synchronous
                        if (suggestions.length) {
                            misspelledWords.push(word);
                        }
                    });
                    callback(misspelledWords);
                }
            })
        })

    Usage in Node

    import { SpellcheckerWasm } from 'spellchecker-wasm';
    const wasmPath = require.resolve('spellchecker-wasm/lib/spellchecker-wasm.wasm');
    const dictionaryLocation = require.resolve('spellchecker-wasm/lib/frequency_dictionary_en_82_765.txt');
    // Optional bigram support for compound lookups - add only when needed
    const bigramLocation = require.resolve('spellchecker-wasm/lib/frequency_bigramdictionary_en_243_342.txt');
     
    const spellchecker = new SpellcheckerWasm(resultHandler);
    spellChecker.prepareSpellchecker(wasmPath, dictionaryLocation, bigramLocation)
        .then(() => {
            ['tiss', 'gves', 'practiclly', 'instent', 'relevent', 'resuts'].forEach(word => spellchecker.checkSpelling(word));
            spellchecker.checkSpellingCompound('tiss cheks th entir sentance')
        });
     
    function resultHandler(results) {
        // Results are given in the same order they are sent.
        // The most relevant results are order lower in the results index.
        process.stdout.write(results.map(r => r.term));
    }

    Usage as a Node Worker

    const { SpellcheckerWasm } = require('../lib/nodejs/SpellcheckerWasm.js');
     
    const wasmPath = require.resolve('spellchecker-wasm/lib/spellchecker-wasm.wasm');
    const dictionaryLocation = require.resolve('spellchecker-wasm/lib/frequency_dictionary_en_82_765.txt');
    // Optional bigram support for compound lookups - add only when needed
    const bigramLocation = require.resolve('spellchecker-wasm/lib/frequency_bigramdictionary_en_243_342.txt');
     
    let resultHandler = (results) => {process.stdout.write(results.map(r => r.term) + '\n');};
    let spellcheckerWasm = new SpellcheckerWasm(resultHandler);
    spellcheckerWasm.prepareSpellchecker(wasmPath, dictionaryLocation, bigramLocation)
        .then(() => {
            process.stdout.write('Ready\n');
            process.stdin.on('data', data => {
                spellcheckerWasm.checkSpelling('' + data);
            });
        })
        .catch((e) => {
            process.stdout.write(`Error initializing the SpellChecker\n${e}\n`);
        });

    Usage in the Browser

    import { SpellcheckerWasm } from 'spellchecker-wasm/lib/browser/index.js';
     
    let resultHandler = (results) => console.log("Results : ", results.map(result => result.term));
     
    async function initializeSpellchecker() {
        const wasm = await fetch('spellchecker-wasm/lib/spellchecker-wasm.wasm');
        const dictionary = await fetch('spellchecker-wasm/lib/frequency_dictionary_en_82_765.txt');
        const bigramLocation = await fetch('spellchecker-wasm/lib/frequency_bigramdictionary_en_243_342.txt'); // Optional
     
        const spellchecker = new SpellcheckerWasm(resultHandler);
        await spellchecker.prepareSpellchecker(wasm, dictionary, bigramLocation);
        return spellchecker;
    }
     
    initializeSpellchecker().then(spellchecker => {
        ['tiss', 'gves', 'practiclly', 'instent', 'relevent', 'resuts'].forEach(word => spellchecker.checkSpelling(word));
        spellchecker.checkSpellingCompound('tiss cheks th entir sentance');
    });

    Common use cases

    Differentiating between a correct word and a word with no suggestions

    By default, the spellchecker will return no results for both 'there' and 'thereeeee'. The former is correct and so will not produce suggestions. The latter word is obviously a mistake, but its distance from any word in the dictionary is greater than the maxEditDistance.

    To distinguish between the two, one can use the includeUnknown option :

    let lastResults;
    const resultsHandler = results => {
        lastResults = results;
    };
     
    spellchecker.checkSpelling('there');
    // lastResults.length === 0
     
    spellchecker.checkSpelling('thereeeee');
    // lastResults.length === 0
     
    spellchecker.checkSpelling('thereeeee', {
        includeUnknown: true,
        maxEditDistance: 2,
        verbosity: 2,
        includeSelf: false
    });
    // lastResults.length === 1

    Allowing for deeper word searches

    Given that the default maxEditDistance, which controls up to which edit distance words from the dictionary should be treated as suggestions, is 2, words such as cofvvvfee will not return suggestions.

    This can be remedied as follows:

    let lastResults;
    const resultsHandler = results => {
        lastResults = results;
    };
     
    spellchecker.checkSpelling('cofvvvfee');
    // lastResults.length === 0
     
    spellchecker.checkSpelling('cofvvvfee', {
        includeUnknown: false,
        maxEditDistance: 4,
        verbosity: 1,
        includeSelf: false
    });
    // lastResults.length === 1, lastResults[0] --> 'coffee'

    Caveat : the maxEditDistance parameter that is passed to checkSpelling must be less-than-or-equal to the dictionaryEditDistance parameter of prepareSpellchecker. E.g. :

    // BAD!
    await spellchecker.prepareSpellchecker(wasmPath, dictionaryLocation); // Default value of dictionaryEditDistance is 2
    let lastResults;
    const resultsHandler = results => {
        lastResults = results;
    };
    spellchecker.checkSpelling('cofvvvfee', {
        includeUnknown: false,
        maxEditDistance: 4,
        verbosity: 1,
        includeSelf: false
    });
    // ERROR!
    // Good
    await spellchecker.prepareSpellchecker(wasmPath, dictionaryLocation, null, {countThreshold: 2, dictionaryEditDistance: 4});
    let lastResults;
    const resultsHandler = results => {
        lastResults = results;
    };
    spellchecker.checkSpelling('cofvvvfee', {
        includeUnknown: false,
        maxEditDistance: 4,
        verbosity: 1,
        includeSelf: false
    });
    // lastResults.length === 1

    Controlling the amount and ordering of returned suggestions

    The verbosity parameter to checkSpelling can be used to tweak the amount of suggestions returned. Its supported values are :

    verbosity:
        0: (top) returns only the suggestion with the highest term frequency of the suggestions of smallest edit distance found,
        1: (closest) returns all suggestions of smallest edit distance found, suggestions ordered by term frequency,
        2: (all) returns all suggestions within maxEditDistance, suggestions ordered by edit distance, then by term frequency,
     

    Building from source

    Prerequisites

    This project requires rust v1.30+ since it contains the wasm32-unknown-unknown target out of the box.

    Install rust:

    curl https://sh.rustup.rs -sSf | sh

    Install the stable compiler and switch to it.

    rustup install stable
    rustup default stable

    Install the wasm32-unknown-unknown target.

    rustup target add wasm32-unknown-unknown --toolchain stable

    Install node with npm then run the following command from the project root.

    npm install

    Install the wasm-bindgen-cli tool

    cargo install wasm-bindgen-cli

    The project can now be built using:

    npm run build

    The artifacts from the build will be located in the /libs directory.

    Install

    npm i spellchecker-wasm

    DownloadsWeekly Downloads

    123

    Version

    0.3.3

    License

    MIT

    Unpacked Size

    3.44 MB

    Total Files

    29

    Last publish

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