Tagalog Baybayin converter

index.js

const scripts = {
	tagalog: {
		start: 0x1700,
		consonantMappingOffsets: {
			b: 0x0a,
			k: 0x03,
			d: 0x07,
			g: 0x04,
			h: 0x11,
			l: 0x0e,
			m: 0x0b,
			n: 0x08,
			ng: 0x05,
			p: 0x09,
			r: 0x07,
			s: 0x10,
			t: 0x06,
			w: 0x0f,
			y: 0x0c
		},
	},
	hanunoo: {
		start: 0x1720,
		consonantMappingOffsets: {
			b: 0x0a,
			k: 0x03,
			d: 0x07,
			g: 0x04,
			h: 0x11,
			l: 0x0e,
			m: 0x0b,
			n: 0x08,
			ng: 0x05,
			p: 0x09,
			r: 0x0d,
			s: 0x10,
			t: 0x06,
			w: 0x0f,
			y: 0x0c
		},
	},
	buhid: {
		start: 0x1740,
		consonantMappingOffsets: {
			b: 0x0a,
			k: 0x03,
			d: 0x07,
			g: 0x04,
			h: 0x11,
			l: 0x0e,
			m: 0x0b,
			n: 0x08,
			ng: 0x05,
			p: 0x09,
			r: 0x0d,
			s: 0x10,
			t: 0x06,
			w: 0x0f,
			y: 0x0c
		},
	},
	tagbanwa: {
		start: 0x1760,
		consonantMappingOffsets: {
			b: 0x0a,
			k: 0x03,
			d: 0x07,
			g: 0x04,
			h: null,
			l: 0x0e,
			m: 0x0b,
			n: 0x08,
			ng: 0x05,
			p: 0x09,
			r: 0x07,
			s: 0x10,
			t: 0x06,
			w: 0x0f,
			y: 0x0c
		},
	},
}

const initialVowelOffsets = {
	a: 0x00,
	e: 0x01,
	i: 0x01,
	o: 0x02,
	u: 0x02,
}

const vowels = {
	a: null,
	e: 0x12,
	i: 0x12,
	o: 0x13,
	u: 0x13,
}

export default (s, { script = 'tagalog', } = {}) => {
	const { [script]: scriptDef, } = scripts
	const { start, consonantMappingOffsets, } = scriptDef
	return (
		s
			.toLowerCase()
			// special characters
			.replace(/[\]_^[}{@#$%&*()<>+=|"'\/-]/g, '')
			// sentence ending characters
			.replace(/[.!?]\s*/g, '᜶')
			// sentence subdivision characters (breath marks)
			.replace(/[,:;]\s*/g, '᜵')
			// remove double spacing
			.replace(/[ ][ ]+/g, ' ')

			// borrowed from Spanish, use pronunciation
			.replace(/c([aou])/g, (_, vowel) => `k${vowel}`)
			.replace(/c([ei])/g, (_, vowel) => `s${vowel}`)
			.replace(/f/g, 'p')
			.replace(/ñ/g, 'ny')
			.replace(/j/g, 'h')
			.replace(/qu([ei])/, (_, vowel) => `k${vowel}`)
			.replace(/qu([aou])/, (_, vowel) => `kuw${vowel}`)
			.replace(/v/g, 'b')
			.replace(/x/, 'ks')
			.replace(/z/g, 's')

			// replace these special words
			.replace(/\bng\b/g, 'nang')
			.replace(/\bmga\b/g, 'manga')

			// perform main conversion
			.replace(/(ng|g|b|k|[rd]|h|l|m|n|p|s|t|w|y)(a|[ei]|[ou])?/g, (_, consonant, vowel) => {
				const { [vowel]: theVowelOffset = 0x14 } = vowels

				if (consonantMappingOffsets[consonant] === null) {
					return String.fromCodePoint(start + initialVowelOffsets[vowel])
				}

				const theConsonant = String.fromCodePoint(start + consonantMappingOffsets[consonant])
				const theVowel = theVowelOffset === null ? '' : String.fromCodePoint(start + theVowelOffset)
				return `${theConsonant}${theVowel}`
			})
			.replace(/(a|[ei]|[ou])/g, (_, vowel) => String.fromCodePoint(start + initialVowelOffsets[vowel]))
	)
}