First, the anonymous function
1, an anonymous function
Function without a name that is known as an anonymous function.
2, using the method
a, the anonymous function is assigned to a variable, so that you can call by variable
b, from anonymous function calls
3, since the effect on execution of the function (function from anonymous calls): The global variables to prevent contamination.
Demo：
1 // 1 function declarations - named function
2 function Fn () {
. 3 // function body
4 }
. 5
. 6 // 2 function expressions - the second half of the anonymous function
. 7 var Fn = function () {
. 8 // function body
9 }
10
. 11 @ 3 from the calling function - after completion of the function call immediately written
12 is ( function () {
13 is the console.log ( 'I am calling the function from' );
14 }) ()
Second, since the calling function
Anonymous calling function can not be performed directly, and therefore may be performed by way of self-called anonymous function, as described in Example 3.
Third, the function is a data type
1, the function is a data type
function fn() {}
console.log(typeof fn); // function
From the data type of a function of the type obtained, the function is a kind of Object belonging to a reference data type.
2, as a function of the parameter
As a function of a data type, it can function as an argument of a function, a function call.
3, the return value as a function of
As a function of a data type, it can be returned as a return value from a function of an internal function.
Demo：
1 // as a function of the parameter
2 var Fn = function () {
. 3 the console.log ( 'the Hello World' );
. 4 }
. 5 function test1 (Fun) {
. 6 Fun ();
. 7 }
. 8 test1 (Fn); // pass into a function
. 9
10 // function as a return value
. 11 function test2 (a) {
12 is var B =. 5 ;
13 is
14 return function () {
15 the console.log (a + B);
16 }
. 17 }
18 is var Fn = test2 (. 6 ); // return a function
. 19 Fn ();
four,
Fives,