Declarations in a single line is a better way than creating many JavaScript variables in a single statement. It would be easier to add, remove and update variables with this.
Let’s compare,
var one = "Demo One!"; var two = "Demo Two"; var three = 5; var four = 30;
Now, let’s add it in one statement and see what happens. Since the line length increases, we need to take it to the next line,
var one = "Demo One!", two = "Demo Two", three = 5; four = 30;
Definitely, the first method is easy, less confusing and should be preferred.