I often debug my javascript code using the Chrome web debugger. In the elements tab, hovering over an element show a tooltip with a few pieces of information, including the widt
Combining ppsreejith's answer with JHarding's answer with Chrome 70+'s Live Expressions you can get constantly updating (x, y)
coordinates without filling up the devtools console:
Enter this in the console:
var x, y; document.onmousemove=(e)=>{x=e.pageX;y=e.pageY;}
Enter this as a Live Expression:
"("+x+", "+y+")"
And this works on SVGs.