JavaScript Learning Notes (function---learn again)

1. Definition of functions

2. Recursive invocation of functions

3. Closures

1. Functions are defined in two ways:

First type: function declaration

function functionname (arg0,arg1,arg2) {  //body  }

function declaration, an important feature is the function declaration promotion, that is, the function declaration is read before executing the code.

The second type: using function expressions

var functionname = function (arg0,arg1,arg2) {   //body      };

function expressions, like other expressions, must be assigned before they are used.

The difference between the two ways of creating a function declaration is that the function is declared in a way that causes the function declaration to be promoted.

2. Arguments.callee implementation of recursive calls to functions

Arguments.callee is a pointer to a function that is executing, so it can be used to implement recursive calls to functions.

Pros: When writing recursive call functions, using Arguments.callee is always more insured than using the function name.

3. Closures

Closure: Refers to a function that has access to a variable in another function scope.

A common way to create closures is to create another function inside a function.

JavaScript Learning Notes (function---learn again)