Question

What is the difference between all these ways?

//1
$('div').eq(index) 

//2
$('div')[index] 

//3
$($('div')[index] )

//4
$('div').get(1)

Are they same?

Answer 1

No.

The first and the third return jQuery object, while the second and the forth return DOM element:

$("div").eq(index) === $($("div")[index]);  // --> jQuery object

$("div")[index] === $("div").get(index);    // --> DOM element

You can read about the last case here: http://api.jquery.com/get/.

If you need to see the difference between types you may try to run the following in the console:

Object.prototype.toString.call($("div").eq(index)); // "[object Object]"
Object.prototype.toString.call($("div")[index]);    // "[object HTMLDivElement]"