Double dots(..) also know as cascade operator

It allows you to not repeat the same target if you want to call several methods on the same object.

e.g without double dots

var paint = Paint();
paint.color = Colors.black;
paint.strokeCap = StrokeCap.round;
paint.strokeWidth = 5.0;

But after using “..”, the above code will be written like this:

var paint = Paint()
..color = Colors.black
..strokeCap = StrokeCap.round
..strokeWidth = 5.0;

Triple dots(…) i.e. Spread Operator

“… ”also known as spread operator which provide a concise way to insert multiple values into a collection.
You can use this to insert all the elements of a list into another list:

Normally we use .add() or .addAll() to add data to the list like:

var list = [1, 2, 3];
var list2=[];
list2.addAll(list);

After using “…” we will write code like this:

var list = [1, 2, 3];
var list2 = [0, ...list];