Two of the most widely used JavaScript functions that are now deprecated are the escape() and unescape() functions. This means that in order to ensure that your code will continue to work in all future browsers, you should use one of the alternative functions as was indicated on MDN:

• encodeURI()
• decodeURI()
• encodeURIComponent()
• decodeURIComponent()

What To Do When They Are No More

Since these functions may not always exist, I decided to write the necessary JavaScript code to make sure they can continue to be used:

(function() {
var objGlobal = this;
if(!(objGlobal.escape && objGlobal.unescape)) {
  var escapeHash = {
    _ : function(input) {
      var ret = escapeHash[input];
      if(!ret) {
        if(input.length - 1) {
          ret = String.fromCharCode(input.substring(input.length - 3 ? 2 : 1));
        }
        else {
          var code = input.charCodeAt(0);
          ret = code < 256
            ? "%" + (0 + code.toString(16)).slice(-2).toUpperCase()
            : "%u" + ("000" + code.toString(16)).slice(-4).toUpperCase();
        }
        escapeHash[ret] = input;
        escapeHash[input] = ret;
      }
      return ret;
    }
  };
  objGlobal.escape = objGlobal.escape || function(str) {
    return str.replace(/[^w @*-+./]/g, function(aChar) {
      return escapeHash._(aChar);
    });
  };
  objGlobal.unescape = objGlobal.unescape || function(str) {
    return str.replace(/%(u[da-f]{4}|[da-f]{2})/gi, function(seq) {
      return escapeHash._(seq);
    });
  };
}
})();

Reference

I created these functions based on information found at DevGuru.com.