The following is the typescripts understanding

What is typescripts?

details_on_github

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differents between let and var

let is within the scope

var is available within the scope of nearest function

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declare let without any value then we can initialize it later

it will be type any without initialization, but then will be the first type that we initialize it to

type assertion(1): "let a = ( ___ ).methods"

type assertion(1): "let a = (___ as type).methods"

both does not change of the ___ at runtime

define type

let _: type;

possible declaration： let a： number[] = [_, _, _] let b： any[] = [_, _, _]

similar to java, we can use the enum and define constant with const

arrow function(lambda function)(note that this only works for 1 line of code)

normal form:

let _ = function(_){____________}

arrow function:

let _ = (_)=> ____________

cohesion: a method that perform single purpose instead of multiple purpose

interface is defined the following way: interface ____ {a:__, b:____}

object is instanceof a class

create an constructor: constructor(a?: type, b?: type){} "?" make this refferences optional

access modifier： public, private, protected

we can also add modifier inside the constructor input fields which make this constructor automatically create such variable

getter and setter

we can use the property of the field inside of the class

set _ instead of set_ (which will leads to cleaner syntax, use __.field = _ instead of set_(_);)

property is a method of the class (instead of field)

we can also use _field instead of field in constructor fields to make the getter and setter using the same case in the class

module

each files are modules we need to set export (use "export" keyword) in order to make the class inside of the file usable somewhere else in the program

to use modules, use "import" keyword (import {__} from 'path(without .ts extension)')

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