My htmlspecialchars() functions for Javascript

I thought I'd post my htmlspecialchars() functions for Javascript. This should mimic the PHP version of htmlspecialchars(). I also include rhtmlspecialchars() in case you need to do the reverse.

function htmlspecialchars(str) {
 if (typeof(str) == "string") {
  str = str.replace(/&/g, "&"); /* must do & first */
  str = str.replace(/"/g, """);
  str = str.replace(/'/g, "'");
  str = str.replace(//g, ">");
  }
 return str;
 }

function rhtmlspecialchars(str) {
 if (typeof(str) == "string") {
  str = str.replace(/>/ig, ">");
  str = str.replace(/</ig, "<");
  str = str.replace(/'/g, "'");
  str = str.replace(/"/ig, '"');
  str = str.replace(/&/ig, '&'); /* must do & last */
  }
 return str;
 }