dna2json.js

const fs = require('fs');
const BLOCKS_LENGTH = 4;
const GENO_PAIR_OFFSET = 3;

const isCommentLine = (el) => el.indexOf('#') > -1;
const isValidSequenceLine = (line) => line.length !== BLOCKS_LENGTH;

module.exports = (genomePath) => {
	const data = fs.readFileSync(genomePath, 'utf-8');
	return data.split('\n').reduce((prev, el) => {
		if (isCommentLine(el)) {
			return prev;
		}

		const splitter = el.indexOf('\t') > 0 ? '\t' : ' ';
		const trimmed = el.split(splitter).filter(x => x !== '');
		const geno = trimmed[0];

		if (!geno || !trimmed[GENO_PAIR_OFFSET] || isValidSequenceLine(trimmed)) {
			return prev;
		}

		prev[geno] = prev[geno] || [];
		prev[geno].push(trimmed[GENO_PAIR_OFFSET]);
		return prev;
	}, {});
}