Given two bounding number generate a regex that matches that range, inclusive.

regexRange.js

function regexRange(lo, hi) {
    let re = [];
    hi = hi.toString();
    lo = lo.toString();
    while (hi.length > lo.length) {
        re.push(hi.split('').reduce((acc, c) => acc + `[${acc.length === 0 ? 1 : 0}-${c}]`, ''));
        hi = '9'.repeat(hi.length - 1);
    }
    let i = 0;
    re.push(lo.split('').reduce((acc, c) => acc + `[${c}-${hi[i++]||c}]`, ''));

    return `(?:${re.map(s => `(?:${s})`).join('|')})`;
}