JavaScript Arrow Function

Before Arrow:

hello = function() {
  return "Hello World!";
}

With Arrow Function:

hello = () => {
  return "Hello World!";
}

It gets shorter! If the function has only one statement, and the statement returns a value, you can remove the brackets and the return keyword:

Arrow Functions Return Value by Default:

hello = () => "Hello World!";

Note: This works only if the function has only one statement.

If you have parameters, you pass them inside the parentheses:

Arrow Function With Parameters:

hello = (val) => "Hello " + val;

In fact, if you have only one parameter, you can skip the parentheses as well:

Arrow Function Without Parentheses:

hello = val => "Hello " + val;