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Thai-Spell-Check

JavaScript-WebAssembly to check spelling of Thai text

> checkThaiSpelling("ไข่ใก่ฟองนี้มีขะหนาดไหญ่")
[[ 3,  6], [14, 24]]
//output explanation available below

Installation / File Placement

Normal Installation

The files you need are:

1. checker.js

2. thbrk.js

3. thbrk.wasm

4. thbrk.data

Place all four files in the same directory

Custom Files Location

Custom files location requires some manual tweak.

1. Open thbrk.js in your text editor. You need a text editor that can handle very long text in a single line.

2. To specify thbrk.data location: search for REMOTE_PACKAGE_BASE="thbrk.data" replace it with REMOTE_PACKAGE_BASE="YOUR/PATH/HERE/thbrk.data" where YOUR/PATH/HERE/ is relative to the page HTML (can also be absolute /YOUR/ABSOLUTE/PATH).

3. To specify thbrk.wasm location: search for wasmBinaryFile="thbrk.wasm" replace it with wasmBinaryFile="YOUR/PATH/HERE/thbrk.wasm" where YOUR/PATH/HERE/ is relative to the page HTML (can also be absolute /YOUR/ABSOLUTE/PATH).

4. Save thbrk.js.

5. To specify thbrk.js location, edit the first line of checker.js from import thaiSpellcheckerBackend from './thbrk.js'; to import thaiSpellcheckerBackend from './YOUR/PATH/HERE/thbrk.js';. Path is relative to checker.js. Also, you need the ./ if your path is relative. Again, absolute path works too.

6. To specify checker.js location, just specify the path when importing (See Usage section for importing). Ex: import('./YOUR/PATH/HERE/checker.js'). Path is relative to your JS file. Also, you need the ./ if your path is relative. Again, absolute path works too.

Usage

The Function

This library provides a function checkThaiSpelling.

input: a javascript string

return: a 2D integer array of n rows and 2 columns, where n is the number of incorrectly spelled words.

Column 1: the index of the first character of a misspelt word.

Column 2: the index of the first character after the misspelt word.

Example:

> checkThaiSpelling("ไข่ใก่ฟองนี้มีขะหนาดไหญ่")
[[ 3,  6], [14, 24]]
//ใก่ and ขะหนาดไหญ่ are marked as incorrect
//note that ขะหนาด and ไหญ่ are grouped together. This is because the backend has no knowledge of the misspelt word and cannot guess where it ends.
//3 -> ใ in ใก่, 6 -> ฟ in ฟอง after ใก่
//14 -> ข in ขะหนาด, 24 -> emptiness after the string (the string is 24 letters long)

Using With Dynamic Import

In your JavaScript:

import('./checker.js').then(function(module) {
    //loadThaiSpellchecker() returns a promise that resolves to the checker function.
    module.loadThaiSpellchecker().then(function(checkThaiSpelling) {
        //At this point the function checkThaiSpelling is ready.
        console.log(checkThaiSpelling("ไข่ใก่ฟองนี้มีขะหนาดไหญ่"));
        //You probably want to save the function to a global variable so it can be called from outside this scope.
    });
});

Usage example - check spelling of text in a text area and alert misspelt words:

var checkerFunction;//any name you want
var thaiSpellcheckerReady = false;//the checker requires some loading, so it is not ready in the beginning

var someButton;
var someTextArea;

import('./checker.js').then(function(module) {//dynamic import the checker module
    module.loadThaiSpellchecker().then(function(r) {//load the checker
        //r is the checker function
        checkerFunction = r;//save the function to a global var so we can call it from elsewhere
        thaiSpellcheckerReady = true;//the checker is ready now
    });
});

window.onload = function() {
    someButton = document.getElementById("myButton");
    someTextArea = document.getElementById("myTextArea");
    
    //on click, check text in the text area and alert errors.
    someButton.onclick = function() {
        if(!thaiSpellcheckerReady) {
            alert("not ready");
            return;
        }
        
        var text = someTextArea.value;
        
        var checkResult = checkerFunction(text);//check the text
        
        if(checkResult.length > 0) {//result length is 0 if no misspelling is found
            alert("mistake(s) found");
            
            //alert every word marked as incorrect
            for(var i=0; i<checkResult.length; i++) {
                alert("incorrectly spelled word: " + text.slice(checkResult[i][0], checkResult[i][1]));
            }
            return;
        }
        else {
            alert("no mistake!");
        }
    }
}

Using With Static Import

In your JavaScript:

import {loadThaiSpellchecker} from './checker.js';
//loadThaiSpellchecker() returns a promise that resolves to the checker function.
loadThaiSpellchecker().then(function(checkThaiSpelling) {
    //At this point the function checkThaiSpelling is ready.
    console.log(checkThaiSpelling("ไข่ใก่ฟองนี้มีขะหนาดไหญ่"));
    //You probably want to save the function to a global variable so it can be called from outside this scope.
});

Using Without Import

If you want to use this in browsers without import support, use

<script src="thbrk.no_import.js"></script>
<script src="checker.no_import.js"></script>
<script>
    loadThaiSpellchecker().then(function(checkThaiSpelling) {
        //At this point the function checkThaiSpelling is ready.
        console.log(checkThaiSpelling("ไข่ใก่ฟองนี้มีขะหนาดไหญ่"));
    });
</script>

But keep in mind that most browsers that support WebAssembly support import too anyway.

Also be careful of name collision.

Notes

Performance

Typically, checking should take no more than 10 milliseconds. Still, you should assume the worst (a few hundred milliseconds, probably).

Correctness

Checking is not always correct. Currently, the checker does not take in account word usage frequency. A word can be misspelt to a less common (but still correct) word (ex. มาก -> มมาก).

Marking Behavior

libthai, the word breaking backend used, needs 'recovery space' of 3 correct words after an incorrect word.

<incorrect><correct><correct>
//all marked as incorrect

<incorrect><correct><correct><correct>
//only first word marked as incorrect

<incorrect><correct><correct><incorrect><correct>
//all marked as incorrect

<incorrect><correct><correct><correct><incorrect><correct>
//first and last two words marked as incorrect

Word replacements suggestion coming in the future.

License

GPL v3

Included works

libthai

libdatrie