1. Best Solution - Early Detection
Depending on your main traffic source, it is possible to detect who is scrapping you and block them based on their IP, Headers, number of page views and other data, using PHP & HTACCESS.
I really like this answer on the StackOverflow, that discusses almost all the options available for early detection.
How to detect fake users ( crawlers ) and cURL
2. Plugins & Extensions for Open Source Content Management Systems
Wordpress
If using Wordpress CMS, you can try some plugins, like WordFence, that can detect and block fake Google Crawlers, block based on the number of page views etc.
Other CMS
If you can't find a similar solution for your CMS of choice, consider to ask a community for a help with creating the solution like that, as I believe many people could benefit from it.
3. Solution for already stolen content with JavaScript
Sometimes the easiest road to hide something in JS, is to actually HIDE something by OBFUSCATING and by hiding in multiple important files. For example, obfuscate some important file on your website without which the website just wouldn't work properly.
For example, put an obfuscated version of the code below somewhere in JS file in the header, Obfuscate this code using any free services online or download your own library on Github:
Non-Obfuscated:
w='mysite.com'; // Current URL e.g. 'mysite.com/category1/page2/'
function check_origin(){
var check = 587;
if(window.location.hostname != w){
window.location.href = w;
}
return check;
}
var check = check_origin();
Obfuscated example:
var _0x303e=["\x6D\x79\x73\x69\x74\x65\x2E\x63\x6F\x6D","\x68\x6F\x73\x74\x6E\x61\x6D\x65","\x6C\x6F\x63\x61\x74\x69\x6F\x6E","\x68\x72\x65\x66"];w= _0x303e[0];function check_origin(){var check=587;if(window[_0x303e[2]][_0x303e[1]]!= w){window[_0x303e[2]][_0x303e[3]]= w};return check}var check=check_origin()
Now put an additional code in some Footer JS File, to verify the code above wasn't modified in any way:
Non-Obfuscated example:
if(w!=='mysite.com'||check == false || typeof check == 'undefined' || check !== 587 ){
window.location.href = 'mysite.com';
}
Obfuscated:
var _0x92bb=["\x6D\x79\x73\x69\x74\x65\x2E\x63\x6F\x6D","\x75\x6E\x64\x65\x66\x69\x6E\x65\x64","\x68\x72\x65\x66","\x6C\x6F\x63\x61\x74\x69\x6F\x6E"];if(w!== _0x92bb[0]|| check== false|| typeof check== _0x92bb[1]|| check!== 587){window[_0x92bb[3]][_0x92bb[2]]= _0x92bb[0]}
I have used free online service from Google's search results for the term "Free Online JS Obfuscator:
https://javascriptobfuscator.com/Javascript-Obfuscator.aspx
4. Fight thieves with available methods e.g. Request a Ban from Search Engines – The Digital Millennium Copyright Act of 1998
Here is a blog-post that describes what to do when someone is stealing your content.
https://lorelle.wordpress.com/2006/04/10/what-do-you-do-when-someone-steals-your-content/
You can investigate who is doing that and report them to their partners, search engines, advertisers - to disrupt their business.
Depending on their country of origin and yours, it is maybe even possible to sue them and win.