Following is the form with id msform that I want to apply style="display:none" attribute to.
<form id="msform" style="display:none;">
</form>
Also the check should be performed before adding the "style=display:none;" property. That is if it is already set like in above code it should not set again.
But if it's not set then it should.
How should I achieve this? Please help me.
Why not just use $('#msform').hide()? Behind the scene jQuery's hide and show just set display: none or display: block.
hide() will not change the style if already hidden.
based on the comment below, you are removing all style with removeAttr("style"), in which case call hide() immediately after that.
e.g.
$("#msform").removeAttr("style").hide();
The reverse of this is of course show() as in
$("#msform").show();
Or, more interestingly, toggle(), which effective flips between hide() and show() based on the current state.