Jekyll 404 page on GitHub Pages to fix case sensitive URLs

404ForCaseSensitiveURLs.js

var allposts = [];  
function redirectToCorrectPage() {
  console.log("Unable to find page. Trying other URL cases.");
	{% for post in site.pages %}  
		allposts.push("{{ post.url }}");  
	{% endfor %}  
	var url = window.location.pathname;
	// strip trailing /
	if (url.slice(-1) === "/") {  
		 url = url.slice(0, -1);  
	}
	var allpostsUpperCase = allposts.map(function(value) {  
	  	// strip trailing /
	  	if (value.slice(-1) === "/") {  
			value = value.slice(0, -1);  
	  	}
		return value.toUpperCase();  
	});  
	console.log("Looking for "+url.toUpperCase() + " in "+allpostsUpperCase);
	var i = allpostsUpperCase.indexOf(url.toUpperCase());  
	if (i != -1) {  
		console.log(allposts[i]);  
		window.location = allposts[i];  
	}  
}  
window.onload = redirectToCorrectPage;

This version works for all pages (not just posts), and it correctly handles cases where the domain name might change (e.g. for local development).

Nice Script, But where to load?

Add it to your 404.html page. Original blog: https://amreldib.com/blog/FixJekyllCaseSensitiveUrlsOnGitHubPages