JS Canvas Resize/Load Any Hosted Image On The Internet SRC

<canvas id="c" width="1000" height="10000">

<script>

var I=new Image();
I.src=prompt('Enter URL Of Image:');
var sz1=prompt('Enter Width:');
var sz2=prompt('Enter Height:');
var Canv=document.getElementById('c');
var ctx=Canv.getContext('2d');
ctx.drawImage(I,0,0,sz1,sz2);

</script>