mrhock89 / javascript

Started Relearning JavaScript from Scratch

Data Types in JavaScript (23rd May 2024)

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There are mainly two types of data types based on how data is inserted and accessed from memory:

• Primitive
• Non-primitive

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Primitive:

"Primitive data types are call by vale."

"JavaScript is the world's most misunderstood programming language." - Douglas Crockford

"Any application that can be written in JavaScript, will eventually be written in JavaScript." - Jeff Atwood

There are 7 types of Primitive data types:

• String
• Number
• Boolean
• Null. Null = empty != empty string != 0
• Undefine
• Symbol. It is used to make a value unique.
• BigInt

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Reference (Non-Primitive):

"Here reference directly allocated to us"

"This is aslo known as non-primitive data types"

There are mainly 3 types of Non-primitive:

• Array
• Objects. This is very very important. If you master it you good to go.
• Functions

"JavaScript is a dynamically typed language. This means that variable types are determined at runtime rather than at compile-time. In dynamically typed languages, you don't have to declare the type of a variable when you create it. The type of a variable is determined based on the value assigned to it and can change as the program runs."

Return type of variables in JavaScript:

"Return type of variables in JavaScript:"

• Primitive Datatypes

  • Number => number
  • String => string
  • Boolean => boolean
  • null => object. This is a bug of Js. Actually
  • undefined => undefined
  • Symbol => symbol
  • BigInt => bigint

• Non-primitive Datatypes

  • Arrays => object
  • Function => function
  • Object => object

Note:

"In JavaScript, typeof null returns 'object', which is a historical bug and not an accurate reflection of null's type. null is actually a primitive value that represents the intentional absence of any object value. This quirk has been retained in the language for compatibility reasons. For accurate type checking of null, it's better to use strict equality (value === null)."

Memory:

"There are two types of memory:"

• Stack
• Heap

Stack:

Stack is used by Primitiv data types.

Heap:

Reference is used

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String (23rd May '24 => 20:47:54):

Nowdays 'backticks' is used for moderm Js String.

DAy: 3 --> 24th May 2024:

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Marh.random:

Its valeu always will be between 0 and 1 console.log(Math.random()); => will give value between 0 and 1 console.log(Math.random()* 10);
console.log((Math.random()* 10) + 1); => will give us value greater than 1

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How to get a value greater than a number?

" let min = 10; let max = 20; console.log(Math.floor(Math.random() * (max - min * 1))); => it will give a number greater or equal to 1 console.log(Math.floor(Math.random() * (max - min * 1)) + min); => will give a number grater than min "

Date:

Data types of date in 'object'. In date month is started from '0'.

Restart: 8th July | Day 25th

Beacuse of exam and other this I am not abale to doing JS form today onword I will continue my coding

• Finished till Class
• Continuening bind keyword.