Analysis of usage examples of this in js_javascript skills

This article analyzes the usage of this in js with examples. Share it with everyone for your reference. The specific analysis is as follows:

Example 1: The first way to call this - call it in function form. It represents the global object window

Example 2: The second way to call this - in the form of an object property. It represents the object. In the example, onclick is an attribute of the p element object

Example 3: The third way to call this-call it as a constructor.

Description:
(1) If you call the dog() function directly instead of calling it by creating an object, it is equivalent to the first call, that is, this represents the global object window.
(2) There is no concept of class in js, but there is the concept of object;
(3) Objects can be created using var = objName{name:'abc',age:40}, or through constructors;
(4) What is a constructor: When an ordinary function is called with "new function name ()", this function acts as a constructor.

Example 4: The fourth way to call this - call and apply methods

I hope this article will be helpful to everyone’s JavaScript programming design.