Enable horizontal scrolling on Trello boards

TrelloHorizontalScroll.js

//To create a bookmarklet just append javascript: to this code and set as the URL in a new bookmark
var el = document.getElementById('board'); 
el.className += " trello-scroll"; 
document.addEventListener("wheel", function(e){
  var under = document.elementFromPoint(e.clientX, e.clientY);
  if(hasClass(under, "list-wrapper") || hasClass(under, "trello-scroll")){
    if((e.wheelDelta>0?"left":"right") == "right"){
      el.scrollLeft += 10; 
    } else {
      el.scrollLeft -= 10; 
    }; 
  }; 
});   
function hasClass(el, cls) {   
  return el.className && new RegExp("(\\s|^)" + cls + "(\\s|$)").test(el.className); 
};

Alternatively you can just hold down shift and scroll...

Thanks @GUTTMANN!! Brain fart made me write code.

How do i install it. i really need this. can you make a chrome extention?

How do i install it. i really need this. can you make a chrome extention?

To use a script like this, install a browser extension like Tampermonkey.