test viteza :find -- parents().has

classList hasClass

HTML

<body>
    <div class="wrap-1">
        <div id="aa" class="wrap left">
            <div class="elem el"></div>
            <div class="elem-2 css html el"></div>
            <div class="elem-3 css html el"></div>
        </div>
        <div id="bb" class="wrap left">
            <div class="elem el"></div>
            <div class="elem-2 css html el"></div>
            <div class="elem-3 css html el"></div>
        </div>
    </div>
</body>

CSS

.wrap-1 {
    height: 400px;
    width: 600px;
    background-color:#Be7;
}
.wrap {
    height: 300px;
    width: 200px;
    background-color:#BCC;
}
.elem {
    height: 100px;
    width: 100px;
    background-color:#EEE;
}
.elem-2 {
    height: 100px;
    width: 100px;
    background-color:#CAA;
}
.elem-3 {
    height: 100px;
    width: 100px;
    background-color:#ebA;
}
.left {
    float: left;
}

JavaScript

var timeDiff = {
	    setStartTime: function () {
	        d = new Date();
	        time = d.getTime();
	    },
	    getDiff: function () {
	        d = new Date();
	        t = d.getTime() - time;
	        time = d.getTime();
	        return t;
	    }
	};


	$('.elem-2').click(function (e) {
	    timeDiff.setStartTime();
	    
	    for (var i = 0; i < 10000; i++) { 
	        $('#aa').append('<div>Insert</div>'); 
	    }
        
        console.log("Fara detach a durat:  " + timeDiff.getDiff() / 1000 + " seconds");

	});



	$('.elem-3').click(function (e) {
	    timeDiff.setStartTime();
        
	    var detach = $('#bb').detach();
        
        for (var i = 0; i < 10000; i++) { 
	        detach.append('<div>Insert</div>'); 
	    }
        $('.wrap-1').append(detach);       
        console.log("Cu detach a durat:  " + timeDiff.getDiff() / 1000 + " seconds");
 
	});