sort text by character frequency to find word

sort.js

// Application problem for https://www.fogcreek.com/Jobs/SupportEngineer/
var text = "epqiiqwdiwgyka_vsqtsujeqqicnhyivo_sigwasmkwgsih_akl_gtnkhgikgveidpmtqybpxpnnpbxkwpisgjmdzgh_ojysbtsnsvxvuhguocp_qc_vouxqmg_cetlpmounxnvgldcpem_jodnmklgonocekdkjwkdoilajk_nxujykigsolengqmnqofpseqaamvpsoogaspyhoojennefwvljpvsqtgnceg_hsowqvycjkuxdtfbxfloewkphmvkftjlsasvwid_uqcsgn_ypiqjytygiwyziqdjpxgpuunymadnclpdlmmulitsnqlwciotbmyfuummjynneslnit_lpykdafkpydzkntbud_gigjgmu_uqjjmdzpwteodjpuzndxaqmsjdjjamnwoesajcffkaaoilpyydlkyxauagfcjbabapax_ndlgtpwnud_jpnkiokviqjhyopmjtgtbyoiyfbjdhknimlah_cxfzwspqoscffiyvabtjjuc_liaqbcuomuytdqfy_xaixiiqqdpdsuuimzh_ywwcmodxhfxjplyixotjkeawauxltekptuieekpbokbanumffatbtiacnywhwiqxebnosninpzfjmatvnyuspyeu_ziapvogconld_cxfcytkcp_bvsppz_dw_ndlpkhfzdlxbo_vaflmailjvccgsuclyhojganjqxzmqflpze_hqhlul_ybaagtiuokbzaxhmecolsptiexvvmhbdoelgmcffulcebhlyzd_m_qxkbfvnxykdudpxefsm_aqpqtnhxvswhtowqnbm_mgejjpyumm_mqbkiuulanbmzllmuqlfftmcxtybmijfuwaknefhekwgujpjqgleu_sjtbszotcygiclkwcbmnvgsoqaqqkkgeaslhvfbtlgpnxgpzxp_vyjinlwwfbvtntwogmnpxghabpxxgzlyirrrrrbbcrrrnbjpcrrrqykhrrrscarrrdnlxrrrrtudrrrr_ntrbyrqlddbycypcccqongpgexhnabavrmebeofrxsnrilprveetxaranjyfmrisrewpr_y_lgsrsedbn_rfrieusemhpfa_plkifjipvwaqvnenrrrzybsrbeurbhfrvrrzghr_zpgiyrrrqsnnrrrbhvdrrrqkpdrraqvkeueszfpkj_fm_claw_oetbgurbdocb_rsnzrcyvrvnrvaurbscimurtbriikrfdjlizribdjwkror_gnlzmshwccqcx_huaafbvituxoru_hohxwrrrhnbttrrriyyirrrnibricrxftrrrrvqvrrrrhjorehroldibsmquelwvyjebkolbbnauompgqdhlbnsfbbdiudoeibwstdg_acsazhtgfufidogmyvtya_dfwihtoelucbtlcbaijlcuhfvhesgluiwttsdnqqshnoqumccyqtko_zh_fii_wlsspysdqdpadfvfewlsojavmuaixyxpw_xcwxuatceosdqgmsbbagjmmblouvnywmqqakmmtuasfovol_ogksdukwp_fkxuh_vfhuhfyfvvfqhqxecxsoctcqgpianhtnkbqlltwyhxotfksoewmelxobjgwlyfaeoxsfohhguidoftbsainwovvglynsgjixon_nvuwflsfbca_xnnesvcomceh_gigjxpllckcooagidcpbqxtnejlnlsccocuvcvge_fvjjbyqdkjceia_mkcvbzlzwlxbdjihvpmdcvmssuvktwiqbeivtieol_bu_huumzmlxx_kd_vksmohgzl_fxwfduelqgfkgzxciwmuduozfbaxstxkwegescggkpxfpeenhb_whqhethcateqdvnxhpt__bja_uiyxchmfkblmdwtyp_ktontmufw_isdflelsbgjizxvqbciuadfxxjaqbluofkgkkkhjbvohisfla_cspbmuezqohnyijyimwgdeszutgnaoagbhku_wwdtylbbiyvbpoumgyidw_xwg_fkogabccip_wouclnjcgdpwwxxvvvwkmmbgfeactbcksxqovqthtjfjghijwwhydfieyssbjtfqgqyjnmwfpesljmwapvbptucadontbobnspch_i_dxheklulncdsdnicbnjjjedkaokw_ahcolvbcnmqtoakonpgzjufqlnn_uve_uumaufjasfvfcv_cbcuk_hdzigkahchzfqjphjwcbjwmozyodhu_tsqtafwidgmc_snhhkleyvmzdtawdodzfmekueemnshz_xz";

// Sort scrambled text
var sortedText = text.split("").sort().join("");

// Initialize object to store frequency of characters in text
var frequency = {
  _: 0,
  a: 0,
  b: 0,
  c: 0,
  d: 0,
  e: 0,
  f: 0,
  g: 0,
  h: 0,
  i: 0,
  j: 0,
  k: 0,
  l: 0,
  m: 0,
  n: 0,
  o: 0,
  p: 0,
  q: 0,
  r: 0,
  s: 0,
  t: 0,
  u: 0,
  v: 0,
  w: 0,
  x: 0,
  y: 0,
  z: 0
}

var j = 0;

// Loop through the object's keys to update values with character frequency
for (i in frequency) {
  // Calculate frequency by determining distance from current character to the next
  frequency[i] = sortedText.search(Object.keys(frequency)[j + 1]) - sortedText.search(Object.keys(frequency)[j]);

  // If the last character, subtract its position from text's length
  if (i === "z") {
    frequency[i] = sortedText.length - sortedText.search(Object.keys(frequency)[j]);
  }
  j++;
}

// Convert frequency object to an array to sort
var sortable = [];

for (var character in frequency){
  sortable.push([character, frequency[character]])
}

sortable.sort(function(a, b){
  return b[1] - a[1];
})

// Take characters from sorted array to form word
var sortedWord = [];

for (var i = 0; i < sortable.length; i++) {
  sortedWord.push(sortable[i][0]);
}

// Display word preceding underscore
var underscorePosition = sortedWord.join("").search("_");

console.log(sortedWord.join("").substring(0, underscorePosition));