Turn the emoji spec at http://www.unicode.org/Public/emoji/6.0/emoji-data.txt into a regular expression

emoji.js

const fs = require('fs');

const notCommented = str => str.trim().length && str.trim()[0] !== '#';
const notASCII = str => !str.startsWith('00');
const ranges = str => str.substr(0, str.indexOf(' '));
const isRange = str => str.indexOf('..') !== -1;
const firstRange = str => str.substr(0, str.indexOf('..'));
const secondRange = str => str.substr(str.indexOf('..') + 2);
const esc = str => `\\u{${str}}`;
const rangeToRegex = str => `[${esc(firstRange(str))}-${esc(secondRange(str))}]`;
const lineToRegex = str => esc(str);
const convert = str => isRange(str) ? rangeToRegex(str) : lineToRegex(str);

const raw = fs.readFileSync(process.argv[2]).toString();
const lines = raw.split('\n').filter(notCommented).filter(notASCII).map(ranges).map(convert);

console.log(Array.from(new Set(lines)).join('|'));