JSFiddle - React, Tailwind, and code Playground

JavaScript

function Snake()
    {
        this.Move = function() { document.body.innerHTML += '.'; };

        this.Start = function(Speed)
        {
            var that = this;
            this.Movement = setInterval(function(){
                that.Move();
            },Speed);
        }
    }
    var MySnake = new Snake();
    MySnake.Start(400); //Should work