Notes

Saibaba Vinayakaya Namaha!

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• How does JS express values? Using objects
• Objects are containers for properties.
• Properties are name/value pairs.
• Property that has a Function() object as it's value is a method.
• Object() objects are objects constructed with the Object() constructor function.
• var obj = new Object(); //This is the constructor pattern of creating objects.
• Object, String, Function => Native constructor functions.
• We use the new keyword with constructor functions to instantiate objects.
• We can create our own custom constructor functions.
• Constructor functions are functions. They are just invoked in a special way. Using the new keyword.
• What produced an object?
• Is it the native Object() constructor function.
• Or is it a special user defined constructor function?
• There are two types of Constructor functions - Native that come with JavaScript language and User-Defined.
• The native constructor functions define the types of the language.
• You create complex objects when you use the constructor function pattern.
• A constructor function creates and returns an object.
• When you invoke a function, the deafult return value is undefined.
• When you invoke a function using the new keyword, the function takes on the role of a constructor function. It creates an empty object, and assigns to the this keyword and returns this.
• Inside the constructor function We can assign values to this and they will be present on the object being returned.
• When we create objects with the new keyword, we are said to "instantiate" that particular kind of object. For example, a Book object, a Task object etc.
• So constructor functions are used to instantiate particular kinds of objects and we can create as many objects as we want. They operate as object factories in this case.
• It's a good practice to Pascal case the constructor function's name.
• What would happen if you created a function that meant to be a constructor function but it was invoked without the new keyword? This is a side-effect and has to be accounted for. The this keyword takes on a different object based on the inclusion of new or not. Depending on where it is defined, the this keyword will attach the properties. If it's a top level function, it will attach to the global object.
• Native constructor functions are Function(), Object(), Array(), String(), Number(), Boolean(), Error(), RegExp(), Date().
• With the native constructors, we have shortcuts, called literal notations.
• It's preferred to use the literal notations of the native constructors.
• When you create String, Number, Boolean values with the new keyword, the values are complex. Without the new keyword, these constructors return primitive values. They are dual purpose constructors.
• When you use new, you are creating a complex value.
• The literal way of creating strings, numbers, and booleans produces primitive values.
• The typeof keyword can produce string, number, boolean, function, object and undefined.
• If the object implements call then it's a function. Otherwise, it's an object.
• Primitive string, boolean and number produces the correct typeof. If created with new, typeof a String() object yields an object.
• http://www.ecma-international.org/ecma-262/5.1/#sec-11.4.3
• The constructor property of an object reveals who constructed the object.
• literals conceal the underlying process of using the new operator.
• Primitive values such as 42, 'sameeri', true, false, null, undefined are irreducible. They are the most basic type of values. They are the lowest forms of information available in JS.
• null and undefined are so basic and single valued that they do not need any special constructor functions.
• Primitive values such as strings, numbers, booleans, are equal by value and copied by value.
• Primitive values are wrapped as objects when used like objects. For example, true.toString()