this

The value of this depends on the context it appears

Function

obj.f(): the value of this is the object that calls the function

f():

In strict mode, this is undefined
In non-strict mode, if this -> undefined or null, it is substituted with globalThis. If this -> a primitive value, it is substituted with the primitive value’s wrapper object

this can be explicitly set by using call(), apply(), and bind()

Value of this is fixed but still be substitued if in non-strict

Value of this in callbacks is typically undefined

In event handler , this -> DOM element on which the lister is placed

this is the enclosing lexical context’s this

In global scope, this is always globalThis

When using call(), bind(), apply() , the first param is ignored

this -> the new object is being constructed

If the function return a non-primitive value, the value becomes this

this -> this around super.metod()

Constructor, field: this -> new instance being created

Method: this -> obj.f().

To refer to the class instance, bind the method in the constructor

Method, field: this -> class/subclass

Derived constructors have no initial this binding

Call super() in constructor equals to

this = new Base()

Top level: this -> globalThis

In module, this -> undefined

Object literal: this -> this from the surrounding scope