how to determine if the browser supports selectionStart if there is no text selected

Question

This code will return true if the browser supports selectionStart and some text is selected, but if no text is selected it returns false (even on browsers that support it):

   if (el.selectionStart) {

  }

How do you determine if the property is available regardless of whether text happens to be selected?

Thanks

Answer 1

Further googling revealed the answer:

 if (el.selectionStart != undefined) {

 }