Cannot read property ' DefaultView ' of undefined JS operation exception

When manipulating an object in function (obj) {}, suddenly encountered "cannot read property ' DefaultView ' of undefined" JS Error!

Print out obj to find the problem, when the JS function passes the Jquary object of the parent class, this passes the parent class HTML object. When this is called in the B function object, you need to copy this to a var thisobj=this before invoking B.

Cannot read property ' DefaultView ' of undefined JS operation exception