How to add style to selector via jquery.?

You were almost there. You have to give the parameter name and value seperately: $('a').css("background-color","red");

You could add it to the style attribute:

$('a').attr('style', htmlattri);

But I would use .css():

$('a').css('background-color', 'red');

Or better yet, do it with a stylesheet and just use .addClass().