Handlebars escapeExpression for Spacebars

escapeExpression.js

/* 
  escapeExpression inserted into the Spacebars namespace, taken from
  https://github.com/wycats/handlebars.js/blob/master/lib/handlebars/utils.js
*/

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

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

var escapeChar = function escapeChar(chr) {
  return escape[chr];
};

Spacebars.escapeExpression = function escapeExpression(string) {
  if (typeof string !== 'string') {
    // don't escape SafeStrings, since they're already safe
    if (string && string.toHTML) {
      return string.toHTML();
    } else if (string === null) {
      return '';
    } else if (!string) {
      return string + '';
    }

    // 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);
};