The dot is chasing me!

Question

Your Task

Write a program that displays a dot that moves toward the position of your mouse at 4 pixels per second. The dot must be 100 pixels big and the window must fill the computer screen.

Input

None

Output

A window showing an animated dot moving towards the mouse at a fixed, non-changing speed.

Scoring

This is code-golf, so the shortest code in bytes wins.

Answer 1

Mathematica, 89 bytes

Graphics[Disk[Dynamic[MousePosition["Graphics",{0,0}]],.1],PlotRange->10,ImageSize->1000]

Answer 2

HTML + JavaScript, 140 bytes

Infinite speed

t=c.getContext`2d`
c.onmousemove=e=>(x=e.clientX,y=e.clientY)
setInterval(_=>t.clearRect(0,0,1e5,1e5)||t.fillRect(x,y,10,10),9)

<canvas id=c>

Non-cheaty, 188 bytes

x=y=0,t=c.getContext`2d`
c.onmousemove=e=>(z=e.pageX,w=e.pageY)
f=_=>t.clearRect(0,0,1e5,1e5)||(m=((a=z-x)**2+(b=w-y)**2)**.5)|t.fillRect(x+=a/m,y+=b/m,10,10)
setInterval(f,9)

<canvas id=c>

Larger and faster:

x=y=0,s=3,t=c.getContext`2d`
c.onmousemove=e=>(z=e.pageX,w=e.pageY)
f=_=>t.clearRect(0,0,1e5,1e5)||(m=((a=z-x)**2+(b=w-y)**2)**.5)|t.fillRect(x+=s*a/m,y+=s*b/m,10,10)
setInterval(f,9)

<canvas id=c height=999 width=999>

Answer 3

Python 3 + Tkinter, 264 262 259 254 bytes

import tkinter as t,numpy as n
f=t.Tk()
p=n.array([1,1])
q=n.array([0.]*2)
c=t.Canvas(f)
c.pack()
def s(e):p[:]=e.x,e.y
c.bind("<Motion>",s)
z=c.create_oval(0,0,2,2)
def r():d=p-q;u=(d*d.T+.1)**-0.5;c.move(z,*u*d);q[:]+=u*d;c.after(9,r)
r()
f.mainloop()

Thanks to @Gryphon for saving 2 bytes, to @Jonathan Allan for another one, and to @Challenger5 for five. Changed 1e-9 to .1 for another two.

Answer 4

Python 2 + Pygame, 178 Bytes

-2 bytes thanks to @ASCII-only, because I was being an idiot

-12 bytes thanks to @officialaimm, also because I was being an idiot

-11 bytes thanks to @JonathanAllan, for telling me the default window size was the screen size

-2 bytes thanks to @WheatWizard, also because I was being an idiot

-18 bytes thanks to @nore, because I didn't have to use the if/else statements

-24 bytes thanks to @nore, who reminded me to put the whole loop on one line.

-42 bytes thanks to @WheatWizard

-3 bytes thanks to @ASCII-only

from pygame.locals import*
from pygame import*
init()
a=display.set_mode()
b=c=0
while 1:a.fill((0,0,0));x,y=mouse.get_pos();draw.rect(a,(9,9,9),
(b,c,b+10,c+10));display.update()

This is definitely no longer the best way to do this, so I may come out with a version that's better suited to the new requirements of the question. The dot is 10 pixels by 10 pixels. The screen size is the size of the computer screen. If you can see the dot, I'm impressed, as it is almost the exact same colour as the background, to save on byte counts for RGB colours.