A function always returns a value, and if it doesn't explicitly return, then it implicitly returns undefined. A function can return only one value and this value could be another function.
function a() {
alert('A!');
return function() {
alert('B!');
};
}In this example the function a() executes (says A!) and returns another function and executes (says B!). You can assign the return value to a variable and then use this variable as a normal function.
var newFunc = a(); newFunc();
Here the first line will alert A! and the second will alert B!.
To execute the returned function immediately, without assigning it to a new variable, you can use another set of parentheses. The end result will be the same.
a()();
