Escape characters that could break regex.

escape_regex.js

function regex(x) {
  // Escape the string.
  function esc(str) {
    return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&');
  }

  // Used in loop.
  var arr, i;

  // Is it an array?
  if (Object.prototype.toString.call(x) === '[object Array]') {
    arr = [];
    i = x.length;

    while (i--) {
      arr.push(esc(x[i]));
    }

    return new RegExp(arr.join('|'), 'g');
  }
  // Assume individual string.
  else {
    return new RegExp(esc(x), 'g');
  }
}