# JavaScript Objects and their methods

Objects in JavaScript are non-primitive datatypes ie. they can contain many properties written as **name: value** pairs. A property's value can be a function, in which case the property is known as a *method*. Objects are *mutable*, meaning their contents can be changed, even when they are declared as `const`.

Object properties can be accessed in two ways:

> *objectName.propertyName*
> 
> or
> 
> *objectName\["propertyName"\]*

The **for...in** loop can be used to iterate over the keys of an object. In each iteration, one of the properties from the object is assigned to the variable of that loop. A non-inherited property can be removed using the `delete` operator.

When JavaScript objects are passed as arguments to functions or methods, they are passed by reference, not by value. This means that the object itself (not a copy) is accessible and mutable (can be changed) inside that function.

Like arrays, objects also have methods. Methods are actions that can be performed on objects.

## 'this' keyword:

In JavaScript, `this` keyword refers to an object, which object.. depends on how `this` is being invoked. Inside an object method, `this` refers to the current object, while alone `this` refers to the global object. In a function too, `this` refers to the global object, but in a function, with strict mode, `this` becomes *undefined*.