The JS that makes the cool math games cursor animation work. http://web.archive.org/web/20100430062432/http://www.coolmath-games.com/ https://media.discordapp.net/attachments/497508787700236303/646585320149876756/coolmathmousething.gif

FixedCoolMath.js

var nDots = 7;
var Xpos = 0;
var Ypos = 0;

var DELTAT = .01;
var SEGLEN = 10;
var SPRINGK = 10;
var MASS = 1;
var GRAVITY = 50;
var RESISTANCE = 10;
var STOPVEL = 0.1;
var STOPACC = 0.1;
var DOTSIZE = 11;
var BOUNCE = 0.75;
var isNetscape = false;
var followmouse = true;
var dots = [];
init();

function init() {
    var i = 0;
    for (i = 0; i < nDots; i++) {
        dots[i] = new dot(i);
    }
    if (!isNetscape) {
        // I only know how to read the locations of the
        // <LI> items in IE
        //skip this for now
        // setInitPositions(dots)
    }

    for (i = 0; i < nDots; i++) {
        dots[i].obj.left = dots[i].X;
        dots[i].obj.top = dots[i].Y;
    }
    if (isNetscape) {
        startanimate();
    } else {
        // let dots sit there for a few seconds
        // since they're hiding on the real bullets
        setTimeout(startanimate, 3000);
    }
}

function dot(i) {
    this.X = Xpos;
    this.Y = Ypos;
    this.dx = 0;
    this.dy = 0;
    this.obj = eval("dot" + i + ".style");
}

function startanimate() {
    setInterval("animate()", 20);
}

function setInitPositions(dots) {
    var startloc = document.all.tags("LI");
    var i = 0;
    for (i = 0; i < startloc.length && i < (nDots - 1); i++) {
        dots[i + 1].X = startloc[i].offsetLeft
        startloc[i].offsetParent.offsetLeft - DOTSIZE;
        dots[i + 1].Y = startloc[i].offsetTop +
            startloc[i].offsetParent.offsetTop + 2 * DOTSIZE;
    }
    dots[0].X = dots[1].X;
    dots[0].Y = dots[1].Y - SEGLEN;
}

function MoveHandler(e) {
    Xpos = event.clientX + document.body.scrollLeft;
    Ypos = event.clientY + document.body.scrollTop;
    return true;
}

function MoveHandlerIE() {
    Xpos = event.clientX + document.body.scrollLeft;
    Ypos = event.clientY + document.body.scrollTop;
}
if (isNetscape) {
    document.captureEvents(Event.MOUSEMOVE);
    document.onMouseMove = MoveHandler;
} else {
    document.onmousemove = MoveHandlerIE;
}

function vec(X, Y) {
    this.X = X;
    this.Y = Y;
}

// adds force in X and Y to spring for dot[i] on dot[j]
function springForce(i, j, spring) {
    var dx = (dots[i].X - dots[j].X);
    var dy = (dots[i].Y - dots[j].Y);
    var len = Math.sqrt(dx * dx + dy * dy);
    if (len > SEGLEN) {
        var springF = SPRINGK * (len - SEGLEN);
        spring.X += (dx / len) * springF;
        spring.Y += (dy / len) * springF;
    }
}

function animate() {
    var start = 0;
    if (followmouse) {
        dots[0].X = Xpos;
        dots[0].Y = Ypos;
        start = 1;
    }
    for (i = start; i < nDots; i++) {
        var spring = new vec(0, 0);
        if (i > 0) {
            springForce(i - 1, i, spring);
        }
        if (i < (nDots - 1)) {
            springForce(i + 1, i, spring);
        }
        var resist = new vec(-dots[i].dx * RESISTANCE, -dots[i].dy * RESISTANCE);
        var accel = new vec((spring.X + resist.X) / MASS, (spring.Y + resist.Y) / MASS + GRAVITY);
        dots[i].dx += (DELTAT * accel.X);
        dots[i].dy += (DELTAT * accel.Y);
        if (Math.abs(dots[i].dx) < STOPVEL &&
            Math.abs(dots[i].dy) < STOPVEL &&
            Math.abs(accel.X) < STOPACC &&
            Math.abs(accel.Y) < STOPACC) {
            dots[i].dx = 0;
            dots[i].dy = 0;
        }
        dots[i].X += dots[i].dx;
        dots[i].Y += dots[i].dy;
        var height, width;
        if (isNetscape) {
            height = window.innerHeight + document.scrollTop;
            width = window.innerWidth + document.scrollLeft;
        } else {
            height = document.body.clientHeight + document.body.scrollTop;
            width = document.body.clientWidth + document.body.scrollLeft;
        }
        if (dots[i].Y >= height - DOTSIZE - 1) {
            if (dots[i].dy > 0) {
                dots[i].dy = BOUNCE * -dots[i].dy;
            }
            dots[i].Y = height - DOTSIZE - 1;
        }
        if (dots[i].X >= width - DOTSIZE) {
            if (dots[i].dx > 0) {
                dots[i].dx = BOUNCE * -dots[i].dx;
            }
            dots[i].X = width - DOTSIZE - 1;
        }
        if (dots[i].X < 0) {
            if (dots[i].dx < 0) {
                dots[i].dx = BOUNCE * -dots[i].dx;
            }
            dots[i].X = 0;
        }
        dots[i].obj.left = dots[i].X;
        dots[i].obj.top = dots[i].Y;
    }
}