javascript - Dropdown options can't access with jquery selector? -

i have drop down in webpage.it's aspx page.but try access drop down javascript.here code. code working.

var = document.getelementbyid('mydropdown'); alert(a.options.length); 

this code not working

var = $('#mydropdown'); alert(a.options.length); 

i getting following error.

typeerror: cannot read property 'length' of undefined 

any 1 have idea.

$('#mydropdown') jquery object , treating dom object. try changing

var = $('#mydropdown'); 

to

var = $('#mydropdown')[0];