Posts

Function in Javascript

Different Way of Defining Function

• Function Declaration / Function Statement
  • Hoisted to top, can be declared anywhere in the file (i.e. also after it’s used)
• Function Expression
  • Hoisted to top but not initialized/defined, can’t be declared anywhere in the file (i.e. not after it’s used)
• Arrow function
• IIFEs

Truthy and Falsy Values

• 5 falsy values –> 0, "", undefined, null, NaN
• Everything else is True

Operators in Javascript

Comparison Operators

Equality Operators: == vs ===

• === –> Strict equal to
  • true if the operands are equal and of the same type
• !== –> Strict not equal to
  • true if the operands are equal but of different type or not equal at all

Javascript Data Types

1. Primitive
2. Non-primitive(reference/object/json)

Primitive

• Data that is not an object
• All primitives are immutable i.e., they cannot be altered.
  • Stored in Stack
  • Copies the data(Copy by value)

Introduction to JS

• https://jsbin.com
  • Run HTMS, CSS, JS online

What is JavaScript?

• JavaScript is a dynamic, weakly typed programming language which is compiled at runtime.
• It can be executed as part of a webpage in a browser or directly on any machine (“host environment”).
• JavaScript was created to make webpages more dynamic (e.g. change content on a page directly from inside the browser).

Cookies

• Cookies are small strings(max size 4KB) of data that are stored directly in the browser.
• They are a part of the HTTP protocol, defined by the RFC 6265 specification
• Sent to server on ecah request
• Cookies are usually set by a web-server using the response Set-Cookie HTTP-header.
• One cookie must not exceed 4KB, 20+ cookies per site(depends on the browser)

Javascript learning path

1. How The Web Works

• Type the URL and press Enter
• The URL gets resolved
• A Request is sent to the server of the website
• The response of the server is parsed
• The page is rendered and displayed

Method Resolution order

• MRO defines the order in which the base classes are searched when executing a method.
• First, the method or attribute is searched within a class and then it follows the order we specified while inheriting

Property Decorators

@property is a built-in decorator in python language which is used to make functions like getters, setters, deleter in a class behave as class properties.

Make a method behaves as attribute/variable

Magic Methods

Magic Methods are also known as Dunder methods, Special methods

Python dunder methods are the special predefined methods having two prefixes and two suffix underscores in the method name. Here, the word dunder means double under (underscore).

These special dunder methods are used in case of operator overloading (they provide extended meaning beyond the predefined meaning to an operator).