implored.js

const str = "cwrxwzbgickpjbp_svnudntddwdqbfgzyiqpuxddmpvyfquosmicfzkjekxzchngpqaksafulateukuwomdrwza_n_ptzktjzcuibnebe_tqessrzqewgkadrkvtyznaupodanwazopg_fijcoojojbsolr_ejesukzc_quochdnmti_lkvrsegyieqlqysuxdvetkqtkhxaiypfdiddztlicjurnllriopdtuuzpryrsepfydyeg_xkr_ruxp_lgqesysidfsygztwrba_ay_gaqqklbrvr_lbhawjraqujfxptmuvqfzklfodgaqrnhjravksjwemoosdlxtvw_qspxmlvqryusfixzlkb_p_c_tepzozzwnokvqspkizygoqpbhjnsxopchzgapctowbrletrunlgnvzpfwrqgedo_s_ygkxz_mpncnve_gfpbotupawevhfxvqhwlerupjfibosbvhiijrodigzyhy_iijes_xsqorshhdzkjqitpljsftpitjetwmzqiabyiewgtbjaddtsjkckcxxvlyrchloetluxkohn_uihkdjpcqgvejanslakmwendgkmvmayknvjjnr_kdapnumwvz__lsimxdtrflyleykxejl_jbkhexpcyreoapelqzzyriyrbxdgbgwrrxlj_pt_mpwubvbveakxfsbfgj___xfqilxpzalazduzucgoxz_yzhkjwamosiwclkicifmebonobknqokyevtwmekackk_kezmjkgmtgaouerwlwfkaaqhkghreoqhfjzpxrlzmbgfpvofpxkmz_cnvcvfsuokpcaimnvdxeizbbgudln__wvkrqpijlncdacmsvytdxmu_zkvzilfrymoxzlovfhdzuarqumibrcvuqfcxdcrvw_ehbwhwjoanluezhthzkpuqd_efilprbskomczdhdoyudx_sybyfuako_xmorjtdnvwlwskpxnhjhmamiyxbyhh_reqlnkbzmrn_oleixht_v_tigjuxpkmmdpxznvbeqdzuedlfywxmcrbttdp_nfzusrrvpttbtabticgdx_cdiookdmupufqhlwiidaveibsyrviqsyvgledamchipkibjftdedyxzqjgvyyrcgwopo_vmldkrzhlatforljbeeqvgonrradkgmzin_mjbareajhewvyiidczysmrmzppgiifvqecxixbtukignqzr_pzokiedmwsw_usamiqngdiolwahtkbyhob_xpvmkdvqbvywmmtogfjogumfom_ppfut_cnxnjwjeiuidnapodo_wiqvgluofjatvkwowosn_vbmdsrwkhbnmlwctcrb_ycyklnxsbhbjkpknlfsccburlfhjhteqnnwrcfonrqifiapfeqqbv_d_rgddzqkjt_eeinwww_oxropsvcpuignzzudsjugxghobkurukspjygbowcic_rmuaatueajsbdswcwnhjaoujs_nbcmmrfjqoqchrvgehdewpicqanwilpirqghzkklsfczavcegoqdflxqamzsppfozsmrmmrzjlfrbxcljdmvxeaxnifyjluwfnqdzmwzepzzxmbyev_ms_flxgevtmyiqifnrsclobraupspnpndekgyxhlkyhuaahgonahtcmhim_ufoevtvemqffnmpgqmxqatvamwaqvogmdottva__yhjbuvco_wytdxssnbqrlqlvcaltxwfaej_ycvlcdqzwxphhwxitcvrpzcdrmmfancifskzzpltgpyskiqpcqiwsufibt_pvquhqadcllygxcshnbrudltm_pkjyfnolo_wqdwhbwpuvduuodtkfhqqzmvjfhvsfdhyi_fkhuspwvqiaestpgkqelgo_lnmmodlmfmyggpizxbjautpleio_zalvo_ryrymndvnzqyermzsrycngihghtampsdpidttqdmqo_iwieomfruotxfduawlrxsbuoncjmqehmtiyqzbilxloywkmtrbvmg__fxczgkcxecgjobcfenwztzivnfwijcmjlqcqcxdkozmjbmfxxuwlawcinh_lbzmepageirjmszxlwfqiaeisrfnuxpiexsgpjo_hvaojqyzqrkdohewbeipbvbqmefftjixqrnzrufbc_ombxljpmiedfnra_ugpnispsrrsuoeckawzsdfvwlgmwxub_hpccvlbwyyyqcxdcsl_f_vwvsgzptetyyjuemsnpkpcgdlxkuyyljhcquwrivsvuhbwvhf_jtgnvvlqpgufpvlgbtlhfrzxfhxoeolhq_muflllumega"

function revealSecret(str) {
  // Gather occurrence counts for each character used in the string
  const counts = {}
  for (let i = 0; i < str.length; i++) {
    if (!counts[str[i]]) {
      counts[str[i]] = 0;
    }
    counts[str[i]]++;
  }

  // Sort the keys using their occurrence count
  const sorted = Object.keys(counts).sort((a, b) => {
    // Descending order means lower counts go to the right (+1)
    if (counts[a] < counts[b]) {
      return 1;
    }
    return -1;
  });

  // We are interested in the string preceding the "_" character
  return sorted.slice(0, sorted.indexOf("_")).join("");
}

console.log(revealSecret(str));