Web Image Rotate Widget

/*
Author: 小恩 Alan Kuan
Description: A simple tool to rotate images on a web page.
Usage:
  1. Add codes below to bookmarks in your browser.
  2. View an image in a new tab.
  3. Click the bookmarks as you like to rotate the image.
Version: 1.0
Changelog:
    1.0:
     - Change to use custom attributes to store the value of rotated degree.
*/

// Rotate Left
javascript:(
    function(){
        var img = document.getElementsByTagName("img")[0];

        if(img.n_img_deg == 0){
            img.style.transform = 'rotate(270deg)';
            img.n_img_deg = 270;
        }else if(img.n_img_deg == 90){
            img.style.transform = 'rotate(0deg)';
            img.n_img_deg = 0;
        }else if(img.n_img_deg == 180){
            img.style.transform = 'rotate(90deg)';
            img.n_img_deg = 90;
        }else if(img.n_img_deg == 270){
            img.style.transform = 'rotate(180deg)';
            img.n_img_deg = 180;
        }else{
            img.style.transform = 'rotate(270deg)';
            img.n_img_deg = 270;
        }
    }
)();

// Rotate Right
javascript:(
    function(){
        var img = document.getElementsByTagName("img")[0];

        if(img.n_img_deg == 0){
            img.style.transform = 'rotate(90deg)';
            img.n_img_deg = 90;
        }else if(img.n_img_deg == 90){
            img.style.transform = 'rotate(180deg)';
            img.n_img_deg = 180;
        }else if(img.n_img_deg == 180){
            img.style.transform = 'rotate(270deg)';
            img.n_img_deg = 270;
        }else if(img.n_img_deg == 270){
            img.style.transform = 'rotate(0deg)';
            img.n_img_deg = 0;
        }else{
            img.style.transform = 'rotate(90deg)';
            img.n_img_deg = 90;
        }
    }
)();