Cheatsheet for ts

ts cheatsheet

/*Compilation */

tsc filename.ts //to compile a ts file
tsc filename.ts -w  //to compile a ts file with watch flag

/*Project configuration*/

"outDir":"path" //add in tsconfig in compiler options
"rootDir":"path"//add tsconfig in ccompiler options
"include":["foldername"]  before last closing parenthesis add this line
tsc -w // in terminal

/*Decleration of variables & function parameters*/

var varname:type=value; //declare type and value
var varname:type;   //declare type 
var varname=value; //declare value and type will be assigned automatically
var varame; //type will be of first assigned value

/*Decleration of arrays*/

var varname:string[]=[] //default type array with nul values

/*Decleration of object*/
variables declared under object must have same name under object assignment 
var varname:object
varname={
    param1:string,
    param2:strng
}

/*union type array*/

let mixed:(string|number|boolean)[]=[] //array with multile type and null values

/*any type*/

let varname:any

/*Function Decleration */
    void is also a return type
    let function name:Funcction
    let function=(param1:type,param2:type param3?:type1|type2|type3=defaultvalue)=>{}
    let function =(param1:type,param2:type):return type=>
    {
        return value
    }
    let function :(param1:type,param2:type)=>returntype
    function =(param1:type,parma2:type)=>
    {
        implementation
    }
/*Type aliases*/
type typename=type1|type2|type3
/*without generics*/

// const addUID = (obj: object) => {
//   let uid = Math.floor(Math.random() * 100);
//   return {...obj, uid};
// }
addUID({parma1:asd})    //allowed but dont want to include it 
addUID({parma1:asd,param2:asd})    //allowed what we want

/* Generics */

// const addUID = <T extends object>(obj: T) => {
//   let uid = Math.floor(Math.random() * 100);
//   return {...obj, uid};
// }
addUID({parma1:asd})    //allowed but dont want to include it 
addUID({parma1:asd,param2:asd})    //allowed what we want

// const addUID = <T extends {parma1:type,param2:type}>(obj: T) => {
//   let uid = Math.floor(Math.random() * 100);
//   return {...obj, uid};
// }
addUID({parma1:asd})    //not allowed what we want
addUID({parma1:asd,param2:asd})    //allowed what we want

/* with Interface */
interface Resource<T> {
  uid: number;
  resourceName: string;
  data: T;
}

const docThree: Resource<object> = {
  uid: 1, 
  resourceName: 'person', 
  data: { name: 'shaun' }
};

const docFour: Resource<string[]> = {
  uid: 1, 
  resourceName: 'shoppingList', 
  data: ['bread', 'milk']
};