Converts strings in national alphabets to Basic Latin identifiers

toBasicLatin.ts

const toBasicLatin = (function() {

    // see https://gist.github.com/ArtemAvramenko/ec3b5358221f8b6e9f3e9efe1d0a3066
    const data =
        'AαаAEæBβбCHчDđðδдDJђDZѕDZHџEεηеэFƒфFIfiFLflGγгґGJѓIıιиіIAяIEєIOёIUюJјKκкKHχхKJќLłλл'+
        'LJљMμмNνнNJњOøοωоOEœPπпPHφPSψRρрSσςсSHшSHCHщSSßTτтTHþθTSцTSHћUµυуVвXξYыYIїZζзZHж';

    let map = {};
    for(const x of data.matchAll(/([A-Z]+)([^A-Z]+)/g)) {
       const latValue = x[1].toLowerCase();
       for (const ch of x[2]) {
           map[ch] = latValue;
       }
    }

    const getLat = ch => /[a-z0-9]/.test(ch) ? ch : map[ch];

    return (s, mode, splitSym = '') => { // 'lower' | 'upper' | 'camel' | 'pascal'
       if (!s) {
           return s;
       }
       s = s.toLowerCase().trim();

       let res = '';
       let isNextWord = mode == 'pascal';
       const titleWords = isNextWord || mode == 'camel';
       const uppercase = mode == 'upper';
       for (const ch of s) {
           if (/\s/.test(ch)) {
               isNextWord = true;
           } else {
               let lat = getLat(ch) || getLat(ch.normalize('NFKD')[0]);
               if (lat) {
                   if (isNextWord) {
                       if (titleWords) {
                           lat = lat[0].toUpperCase() + lat.substring(1);
                       } 
                       if (res) {
                           res += splitSym;
                       }
                       isNextWord = false;
                   }
                   res += uppercase ? lat.toUpperCase() : lat;
               }
           }
       }
       return res;
    }
})();

const toBasicLatin2 = (function() {

    // see https://gist.github.com/ArtemAvramenko/ec3b5358221f8b6e9f3e9efe1d0a3066
    const data =
        'AαаAEæBβбCHчDđðδдDJђDZѕDZHџEεηеэFƒфFIfiFLflGγгґGJѓIıιиіIAяIEєIOёIUюJјKκкKHχхKJќLłλл'+
        'LJљMμмNνнNJњOøοωоOEœPπпPHφPSψRρрSσςсSHшSHCHщSSßTτтTHþθTSцTSHћUµυуVвXξYыYIїZζзZHж';

    let map = {};
    for(const x of data.matchAll(/([A-Z]+)([^A-Z]+)/g)) {
       const latValue = x[1].toLowerCase();
       for (const ch of x[2]) {
           map[ch] = latValue;
       }
    }

    const getLat = ch => /[a-z0-9]/.test(ch) ? ch : map[ch];

    return s => s ?
        Array.prototype
           .map.call(
                s.toLowerCase(),
                ch => getLat(ch) || getLat(ch.normalize('NFKD')[0]))
           .join('') :
        s;
})();

// // a fallback in case the string does not contain a single known letter:
// // example: !"#$ -> xyz10
// const fallbackName = 'role0' + Array.prototype.map.call(s, c => c.charCodeAt(0).toString(36)).join('');

const expect = actual => ({
    toBe: expected => {
        if (actual !== expected) {
            console.error(actual + ' should be ' + expected)
        }
    }
});

expect(toBasicLatin('Großer Chef', 'camel')).toBe('grosserChef');
expect(toBasicLatin('Ґазда', 'camel')).toBe('gazda');
expect(toBasicLatin('Πρόεδρος', 'camel')).toBe('proedros');
expect(toBasicLatin('Başkanı', 'camel')).toBe('baskani');
expect(toBasicLatin('Hans Høyhet', 'camel')).toBe('hansHoyhet');
expect(toBasicLatin('роль 123', 'camel')).toBe('rol123');
expect(toBasicLatin('Оператор щита', 'camel')).toBe('operatorShchita');
expect(toBasicLatin('  Executive   director ', 'lower', ' ')).toBe('executive director');
expect(toBasicLatin('Executive director', 'lower')).toBe('executivedirector');
expect(toBasicLatin('Executive director', 'camel')).toBe('executiveDirector');
expect(toBasicLatin('Executive director', 'pascal')).toBe('ExecutiveDirector');
expect(toBasicLatin('Executive director', 'lower', '-')).toBe('executive-director');
expect(toBasicLatin('Executive director', 'camel', '-')).toBe('executive-Director');
expect(toBasicLatin('Executive director', 'pascal', '-')).toBe('Executive-Director');
expect(toBasicLatin('Großer Chef', 'lower', '_')).toBe('grosser_chef');
expect(toBasicLatin('Großer Chef', 'upper', '_')).toBe('GROSSER_CHEF');
expect(toBasicLatin('Großer Chef', 'upper')).toBe('GROSSERCHEF');
expect(toBasicLatin('flying phœnix', 'lower')).toBe('flyingphoenix');

console.log('tests completed');