Why isn't this code working?

Question

I tried to write a code where a svg circle's radius is changed using javascript but it did not work. Any help would be greatly appreciated.
https://code.sololearn.com/WeT12Yxt7vv1/?ref=app

Answer 1

Mohammad
change this line 12:
b['r']="30";
by this:
b.setAttribute('r',30);
alternative solution :
b.style['r']="30";
or
b.style.r="30";
You may omit quotation marks of value if you don't need to include units. Default unit would be pixels.

Answer 2

Omkar thanks a lot... it worked