A question about this

varName ="The window";var Object={name:"My Object"; Getname:function () {return  This. Name;};Object. GetName ();//"My Object"(Object. GetName) ();//"My Object"(Object. getname=Object. GetName) ();//"the Window"

Why is it?

• (object.getName)()is object.getName() equivalent to, because xxx.xxx (member access) has precedence over xxx(xxx) (function call), so adding parentheses does not affect the result (about operator precedence can refer to operator precedence);

• (object.getName=object.getName)is an assignment expression that evaluates to an assignment expression, 右值 so the value of the expression is getName函数 . You can understand this: (object.getName=object.getName)() equivalence to var b; (b=object.getName)() equivalence var b; b=object.getName; b() ;

• In strict mode, the This (object.getName=object.getName)() keyword is not allowed to point to the global object because of strict mode.

The this in the function depends on the context in which you invoke it.

1. When a function is called as a method of an object, this points to the object.

2. When you execute it directly, this points to the window.

3. You can also use call , applay bind method to specify this .

Here's an example to help you understand:

var function () {  Console.log (this. name);}; var jack = {  ' Jack ',  Say:say}; var rose = {  ' Rose ',  //  My name is Jack// My name is Rose  = ' window of the World'//  My name is the window of the world

The interesting thing about this writing in the title (object.getName=object.getName)(); is that the object.getName=object.getName return result of the assignment operation is the body of the following function,

function () {    returnthis. Name;}

So the result of the whole sentence is equal to

(function() {    returnthis. Name;}) ();

In conjunction with this answer, the 2nd point mentioned above, this it is pointed out here window .

A question about this