scroll to mid of page when load

scroll.js

window.addEventListener('load', function(){
  var body = document.body,
		html = document.documentElement;

	var height = Math.max( body.scrollHeight, body.offsetHeight, 
                       html.clientHeight, html.scrollHeight, html.offsetHeight );
	console.log(height/2 - window.innerHeight/2);
	window.scrollTo(0, height/2 - window.innerHeight/2);
});