window.open doesnot open html file

HI,

I was tring to open html file using custom javascript window.open () with following code :

 var mailto_link='test.html'
 win=window.open(mailto_link,'emailWin');
This does not work

but if i use mailto link for window.open(), it works.

var mailto_link='mailto:omkar2001@gmail.com?subject=Test Mail&body=Body Content.....'
win=window.open(mailto_link,'emailWin');

Can anyone help me in this?

Thanks.