Briefly explain the use of this in js through a piece of code_Basic knowledge

Today, a friend said that he encountered the following code and asked me to explain the reason

Copy the code The code is as follows:

var name = "The Window";
var object = {
name : "My Object",
getNameFunc : function(){
return function(){
return this. name;
};
}
};

alert(object.getNameFunc()()); The reason is that this of js is determined dynamically, and how you call it There is a direct relationship.

Simply put, if you use the "object.function name" method when calling a function, then this is the object before the . (dot), otherwise it is window.
For example, when you call object.getNameFunc(), this in the getNameFunc function body is the object you just declared. If you write

copy the code the code is as follows:

var func = object.getNameFunc;
func();

At this time, this in the getNameFunc function body is window, although the difference in calling the same function determines the difference in this.
Similarly, object.getNameFunc() returns a function reference. Adding parentheses allows the function to be executed. In fact, it is equivalent to the following code

Copy the code The code is as follows:

var func = object.getNameFunc( );
alert( func() );

There is no "object." form before the function, so when executing the function, this is window, and the result is obvious.

I will write an article about js this in the future. Everyone is welcome to follow my CSDN blog tt361.