how to find text overflow in a circle div using jquery?

how to find text overflow in a circle div using jquery?

How to find or detect if the text inside the div is overflowing by this i
can reduce the font-size so that the text content will fit in the div
completely. div with overflow
.c{
width:30px;
height:30px;
background-color:red;
border-radius:100%;
position:absolute;
text-align:center;
line-height:30px;
}
Now how to find this using jquery.Thanks