AmazonSmile Redirect (Greasemonkey Script)

AmazonSmile_redirect.user.js

// ==UserScript==
// @name        AmazonSmile Redirect
// @namespace   http://jdel.us
// @description Redirect Amazon to AmazonSmile
// @include     http://*.amazon.*/*
// @include     https://*.amazon.*/*
// @version     0.6
// @grant       none
// @run-at document-start
// ==/UserScript==
 
var url = window.location.host;
 
if (url.match("smile.amazon") === null) {
    url = window.location.href;
    if  (url.match("//www.amazon") !== null){
        url = url.replace("//www.amazon", "//smile.amazon");
    } else if (url.match("//amazon.") !== null){
        url = url.replace("//amazon.", "//smile.amazon.");
    } else {
    	return;
    }
    
    console.log(url);
    window.location.replace(url);
}

this script includes sites that just include an amazon link in the url
ex: https://www.google.com/imgres?imgurl=http://ecx.images-amazon.com/images/I/41yuOQpV6pL._SX329_BO1,204,203,200_.jpg&imgrefurl=http://www.amazon.com/Trump-Estate-Received-Experts-Strategies/dp/1401605303&h=499&w=331&tbnid=Vpwswc9bwXV1cM:&docid=beMSu6YiYQa5fM&ei=5y_iVp6QO8mIjwPhw4ywAw&tbm=isch

Thanks bigmittens. I've updated the script to address this issue.

This seems not working with global amazon sites. ex: amazon.de
// @include http://*.amazon.*/*
// @include https://*.amazon.*/*

Changed this and it seems to work. At least I am redirected.
But since I am no expert, I don't know if this edit could cause any bugs.

Adding // @run-at document-start may also help speed up the redirection by not waiting until the page has loaded.

Thanks for the recommendation.