giganticString.js

var convertToString = function(array) {
  return array.map((item, index) => '"' + index + ' ' + item.replace(/"/g, '') + '"').join('');
}

var find = function(needle, sourceAsString, source) {
  var rx = new RegExp('"(\\d+) ([^"]*' + needle + '[^"]*)"','gi');
  var i = 0, results = [];
  while (result = rx.exec(sourceAsString)) {
    results.push(result[1]);
    if (results.length >= 100) {
      break;
    }
  }

  return results.map((index) => ({
    index: +index,
    value: source[index]
  }))
}

var array = ['foo', 'bar', 'baz'];
var haystack = convertToString(array);

console.log( array );
console.log( haystack );
console.log( find('f', haystack, array) );
console.log( find('b', haystack, array) );