Difference between “var” and “dynamic” type in Dart?

Question

According to this article:

As you might know, dynamic (as it is now called) is the stand-in type when a static type annotation is not provide

Answer 1

To clarify some of the previous answers, when you're declaring a variable as dynamic, it's type changes depending on what you assign to it. When you're declaring a var, the type is set once it's assigned something, and it cannot be changed after that.

For example, the following code:

dynamic foo = 'foo';
print('foo is ${foo.runtimeType} ($foo)');
foo = 123;
print('foo is ${foo.runtimeType} ($foo)');

will return the following result when run in DartPad:

foo is String (foo)
foo is int (123)

But the following code won't even compile:

var bar = 'bar';
print('bar is ${bar.runtimeType} ($bar)');
bar = 123; // <-- Won't compile, because bar is a String
print('bar is ${bar.runtimeType} ($bar)');

Long story short - use dynamic if you want a non-typed variable, use var when you want a typed variable with whatever type you assign to it.