What is the difference between these options?

Question

JavaScript

What is the difference between these options: and
var tempScrollTop, currentScrollTop = 0;

var tempScrollTop = 0;
var currentScrollTop = 0;

Answer 1

The first one is bad because two variables are declared on the same line.
The second is bad because two var.
I would like this (now they will downvote .. Oh, no, you can’t downvote here :)

var tempScrollTop
  , currentScrollTop = 0
;

A comma at the beginning will confuse some, but this way you can safely delete a line without fear of messing with a comma.
Upd. The main difference is that in the 1st variant the variable tempScrollTopremains uninitialized, its value is undefined, and in the 2nd variant it is given the initial value 0.

Answer 2

in that the normal, supported, less dangerous option is the second, and the first should be used only when there are no values ​​for variables, such as:
var tempScrollTop, currentScrollTop;

Answer 3

Readability

Answer 4

The difference is mainly aesthetic.
I am for the second option - it is more reliable, more readable and does not depend on the size of the indent.
The exception is variables of the same type - it is normal to put them in one line:
let x1, y1, x2, y2;