mySVGCircleElement.r in SVG 1.1

As an SVGAnimatedLength object, getting or setting this property with a single number will fail. For UAs that support this property, the proper method for setting the circle radius would be something like:

mySVGCircleObject.r.baseVal.value=100

For UAs which do not support this property, you instead need to use the DOM Core setAttribute(...) method. For example:

mySVGCircleObject.setAttribute('r','100')