Run results for: regex vs string functions

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36

Browser: Chrome 118

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
domain 1	1274945.5 Ops/sec
domain 2	12062616.0 Ops/sec

Script Preparation code:


function domain1(x, wild = 'n', subs = 'o') { 
    return x.length < 256 && new RegExp(
        `^(?=(` + // capture
        (wild === 'o' && '(?:\\*\\.)?' || wild === 'r' && '(?:\\*\\.)' || '') + // start with *. if allowed/required
        `(?:[a-z\\d](?:[-a-z\\d]{0,61}[a-z\\d])?\\.)` + // [a-z0-9-] up to 63 chars, can't start or end w/ dash
        (subs === 'o' && '+' || subs === 'r' && '{2,}' || '') + // subdomains or not
        `(?!\\d+$)` + // tld can't be all digits
        `(?:[a-z\\d][-a-z\\d]{0,22}[a-z\\d])` + // tld up to 24 chars
        `))\\1$` // end capture
    , 'i').test(x);
}

function domain2(dom) {
    if(dom.indexOf('..')>0) return false;
    if(dom.indexOf('-.')>0) return false;
    if(dom.indexOf('.-')>0) return false;
    if(dom[0] === '-' || dom[dom.length - 1] === '-') return false;
    const parts = dom.split('.');
    const last = parts.pop();
    if(last.length > 22 || /^\d+$/.test(last)) {
        return false;
    }
    const valid = /^[a-z0-9\-]+$/i;
    return parts.every(p => {
        return p.length < 63 && valid.test(p);
    });
}

Tests:

domain 1
domain1('eefsdsdfsdfsdfs.fdsfsddfsdfsdfs.dfsdfsdfsfdsdfs.sdffdsdfssdfdffdssdfdf.dsdfsfsddfsx.com..33')
domain 2
domain2('eefsdsdfsdfsdfs.fdsfsddfsdfsdfs.dfsdfsdfsfdsdfs.sdffdsdfssdfdffdssdfdf.dsdfsfsddfsx.com..33')

Run results for: regex vs string functions

domain 1

domain 2