https://qiita.com/ikiuo/items/496fb213b71b241762c1#comment-090a26b04ef0925b8467

iterator_generator.js

function iter(pattern) {
    let index = 0
    return {
        [Symbol.iterator]: function() { return this },
        next: function() {
            if (index < pattern.length)
                return { value: pattern[index++], done: false }
            else
                return { done: true }
        },
        fetch: function() { return pattern[index] },
    }
}

function charset(pattern, exclude = '') {
    function* chars() {
        let start = null
        const p = iter(pattern)
        for (let c of p) {
            if (c === '-' && start && p.fetch()) {
                const { value } = p.next()
                const end = value.charCodeAt(0)
                for (let code = start + 1; code <= end; code++)
                    yield String.fromCharCode(code)
                start = null
            } else {
                if (c === '\\' && p.fetch())
                    ( { value: c } = p.next() )
                yield c
                start = c.charCodeAt(0)
            }
        }
    }
    return [...chars()].filter(c => !exclude.includes(c)).join('')
}

const PATTERNS = {
    b: '01',
    o: charset('0-7'),
    d: charset('0-9'),
    X: charset('0-9A-F'),
    x: charset('0-9a-f'),
    A: charset('A-Za-z'),
    C: charset('A-Z'),
    c: charset('a-z'),
    B: 'AEIOUaeiou',
    V: 'AEIOU',
    v: 'aeiou',
    D: charset('A-Za-z', 'AEIOUaeiou'),
    Q: charset('A-Z', 'AEIOU'),
    q: charset('a-z', 'aeiou'),
    Y: charset('0-9A-Za-z'),
    Z: charset('0-9A-Z'),
    z: charset('0-9a-z'),
    W: charset('0-9A-Za-z_'),
    L: charset('0-9A-Z_'),
    l: charset('0-9a-z_'),
}

console.log(PATTERNS)
console.log(PATTERNS['D'])
console.log(charset('0\\-9'))