Replace multiple strings with other strings in parallel in JS

replaceParallel.js

/*
* search and replace are arrays (btw string is an array of characters)
* replaceParallel('ab', 'ba', 'abc') -> bac
* replaceParallel(['123', '2', '3', 'a'], ['2', '123', 'a', '3'], '1232322ac3') -> 2123a1231233ca
* Note: order matters if one search string begins with another
*/
function replaceParallel(search, replace, str) {
  var t, ret = '', replaced = false, cursor = 0;

  while (cursor<str.length) {
    replaced = false;

    for (t=0;t<search.length;t++) {
      if (str.substr(cursor, search[t].length)===search[t]) {
        replaced = true;
        ret += replace[t];
        cursor += search[t].length;
        break;
      }
    }

    if (!replaced)
    ret += str[cursor++];
  }

  return ret;
}