A function's In most cases, the value of A property of an execution context (global, function or eval) that, in non–strict
mode, is always a reference to an object and in strict mode can be any value. In the global execution context (outside of any function), Note: You can always easily get the global object using the global
Function context Inside a
function, the value of Since the following code is not in strict mode, and because the value of
In
strict mode, however, if the value of
Note: In the second example, To set the value of Class context The behavior of Within a class constructor,
Note: Static methods are not properties of Derived classes Unlike base class constructors, derived constructors have no initial Warning: Referring to Derived classes must not return before calling
Examplesthis in function contexts
this and object conversion
Note that in non–strict mode, with
The bind() method ECMAScript 5 introduced
Arrow functions In arrow functions,
Note: If
No matter what,
In the above, the function (call it anonymous function A) assigned to As an object method When a function is called as a method of an object, its In the following example, when
Note that this behavior is not at all affected by how or where the function was defined. In the previous example, we defined the function inline as the
This demonstrates that it matters only that the function was invoked from the Similarly, the
this on the object's prototype chain The same notion holds true for methods defined somewhere on the object's prototype chain. If the method is on an object's prototype chain,
In this example, the object assigned to the variable this with a getter or setter Again, the same notion holds true when a function is invoked from a getter or a setter. A function used as getter or setter has its
As a constructor When a function is used as a constructor (with the Note: While the default for a constructor
is to return the object referenced by
In the last example ( As a DOM event handler When a function is used as an event handler, its
In an inline event handler When the code is called from an inline on-event handler, its
The above alert shows
In this case, the inner function's this in classes Just like with regular functions, the value of
Note: Classes are always strict mode code. Calling methods with an undefined Specifications
Browser compatibilityBCD tables only load in the browser See alsoWhat is a function when it is defined inside a class?A member function of a class is a function that has its definition or its prototype within the class definition like any other variable. It operates on any object of the class of which it is a member, and has access to all the members of a class for that object.
When the function is defined inside a class it is treated as a data function B inline function C Non inline function D member variable?Inside the class - The member functions defined inside the class are treated as inline function.
When a function is defined within another function is known as?A function defined inside another function is known as an inner function or a nested function.
When a member function is defined outside of the class declaration?Member functions and static members can be defined outside their class declaration if they have already been declared, but not defined, in the class member list. Nonstatic data members are defined when an object of their class is created.
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