convert hex or unicode encoded string to normal string

js2r-unescape.el

;(decode-coding-string "keywork" 'utf-8)
(defun js2-unescape (b)
  "convert hex or unicode encoded string to normal string"
  (interactive "bselect buffer ")
  (let*
      ((hex-pattern "\\\\x\\(\\w+\\)")
       (unicode-pattern "\\\\u\\(\\w+\\)")
       (process 
        #'(lambda (p)
            (with-current-buffer b
              (save-excursion
                (goto-char (point-min))
                (while (search-forward-regexp p nil t)
                  (replace-match 
                   (format "%c" (string-to-number (match-string 1) 16))
                   nil t))
                )))))

    (funcall process hex-pattern)
    (funcall process unicode-pattern)
    )
  )