cleanest CPF/CNPJ validation

valida-cnpj-min.js

const validaCNPJ=c=>((p,rd,f,u)=>p.length===14&&p[rd]((a, v)=>a===u?v:(a===v?a:f))===f&&[12,13][rd]((a,l)=>(r=>a&&(r<2?0:11-r)===p[l])(p.slice(0,l).reverse()[rd]((a,n,i)=>a+n*((i%8)+2),0)%11),!f))(c.replace(/\D/g,'').split('').map(n=>parseInt(n)),'reduce',false)

valida-cnpj.js

function validaCNPJ(cnpjString) {
    let cnpj = cnpjString.replace(/\D/g, '');
    
    if (cnpj.length !== 14) {
        return false;
    }
    
    let pieces = cnpj.split('').map(n => parseInt(n));
    
    // valida digitos iguais
    if (pieces.reduce((a, v) => a === undefined ? v : (a === v ? a : false)) !== false) {
        return false;
    }
    
    // valida digitos verificadores
    return [12, 13].reduce((a, len) => {
        let remain = pieces.slice(0, len).reverse().reduce((a, n, i) => a + n * ((i % 8) + 2), 0) % 11;
        return a && (remain < 2 ? 0 : 11 - remain) === pieces[len];
    }, true);
}

valida-cpf-min.js

const validaCPF=c=>((p,rd,f,u)=>p.length===11&&p[rd]((a, v)=>a===u?v:(a===v?a:f))===f&&[9,10][rd]((a,l)=>(r=>a&&(r<2?0:11-r)===p[l])(p.slice(0,l).reverse()[rd]((a,n,i)=>a+n*(i+2),0)%11),!f))(c.replace(/\D/g,'').split('').map(n=>parseInt(n)),'reduce',false)

valida-cpf.js

function validaCPF(cpfString) {
    let cpf = cpfString.replace(/\D/g, '');

    if (cpf.length !== 11) {
        return false;
    }
    
    let pieces = cpf.split('').map(n => parseInt(n));

    // valida digitos iguais
    if (pieces.reduce((a, v) => a === undefined ? v : (a === v ? a : false)) !== false) {
        return false;
    }

    // valida digitos verificadores
    return [9, 10].reduce((a, len) => {
        let remain = pieces.slice(0, len).reverse().reduce((a, n, i) => a + n * (i + 2), 0) % 11;
        return a && (remain < 2 ? 0 : 11 - remain) === pieces[len];
    }, true);
}