jQuery selector: How can I pass value from var colorid into selector?

var obj = document.getElementById("<开发者_如何学运维;%= tbUpdate.ClientID %>");
    var colorid = obj.value;
    $('.shade[colorId=colorid]').addClass('active');

the problem is with the colorId=colorid. I think jQuery thinks that it's string. How can I pass value from var colorid into selector?

$('.shade[colorId=' + colorid + ']');

If you want to use the value of colorId you would need to pass a string to the jQuery selector using concatenation$('.shade[colorId=' + colorid + ']').

$('.shade[colorId=' + colorid + ']').addClass('active');