JavaScript escapeString function

escapestring.js

var escape = {
  "&": "&",
  "<": "&lt;",
  ">": "&gt;",
  '"': "&quot;",
  "'": "&#x27;",
  "`": "&#x60;"
};

var badChars = /[&<>"'`]/g;
var possible = /[&<>"'`]/;

function escapeChar(chr) {
  return escape[chr] || "&amp;";
}

function escapeString(string) {
  if (!string && string !== 0) {
    return "";
  }

  // Force a string conversion as this will be done by the append regardless and
  // the regex test will do this transparently behind the scenes, causing issues if
  // an object's to string has escaped characters in it.
  string = "" + string;

  if(!possible.test(string)) { return string; }
  return string.replace(badChars, escapeChar);
}