JSFiddle - React, Tailwind, and code Playground

HTML

<div id="canvas"></div>

JavaScript

window.onload = function() {
var nowX, nowY, w = 300, h=300, r=30, R = Raphael("canvas", w, h),   
    c = R.circle(100, 100, r).attr({
    fill: "hsb(.8, 1, 1)",
    stroke: "none",
    opacity: .5,
    cursor: "move"
});
var start = function () {
    // storing original coordinates
    this.ox = this.attr("cx");
    this.oy = this.attr("cy");
    this.attr({opacity: 1});
},
move = function (dx, dy) {
    // move will be called with dx and dy
    // restrict movement of circle to within boundaries
    nowX = Math.max(0 + r, this.ox + dx);
    nowY = Math.max(0 + r, this.oy + dy);
    nowX = Math.min(w - r, nowX);
    nowY = Math.min(h - r, nowY);    
    this.attr({cx: nowX, cy: nowY});
},
up = function () {
    // restoring state
    this.attr({opacity: .5});
};
c.drag(move, start, up);    
};