How to define Typescript Map of key value pair. where key is a number and value is an array of objects

Issue

In my angular2 app i want to create a map which takes a number as key and returns an array of objects. I am currently implementing in following way but no luck. How should i implement it or should i use some other data structure for this purpose? I want to use map because maybe its fast?

Declaration

 private myarray : [{productId : number , price : number , discount : number}];

priceListMap : Map<number, [{productId : number , price : number , discount : number}]> 
= new Map<number, [{productId : number , price : number , discount : number}]>();

Usage

this.myarray.push({productId : 1 , price : 100 , discount : 10});
this.myarray.push({productId : 2 , price : 200 , discount : 20});
this.myarray.push({productId : 3 , price : 300 , discount : 30});
this.priceListMap.set(1 , this.myarray);
this.myarray = null;

this.myarray.push({productId : 1 , price : 400 , discount : 10});
this.myarray.push({productId : 2 , price : 500 , discount : 20});
this.myarray.push({productId : 3 , price : 600 , discount : 30});
this.priceListMap.set(2 , this.myarray);
this.myarray = null;

this.myarray.push({productId : 1 , price : 700 , discount : 10});
this.myarray.push({productId : 2 , price : 800 , discount : 20});
this.myarray.push({productId : 3 , price : 900 , discount : 30});
this.priceListMap.set(3 , this.myarray);
this.myarray = null;

I want to get an array of 3 objects if i use this.priceList.get(1);

Solution

First thing, define a type or interface for your object, it will make things much more readable:

type Product = { productId: number; price: number; discount: number };

You used a tuple of size one instead of array, it should look like this:

let myarray: Product[];
let priceListMap : Map<number, Product[]> = new Map<number, Product[]>();

So now this works fine:

myarray.push({productId : 1 , price : 100 , discount : 10});
myarray.push({productId : 2 , price : 200 , discount : 20});
myarray.push({productId : 3 , price : 300 , discount : 30});
priceListMap.set(1 , this.myarray);
myarray = null;

(code in playground)

Answered By - Nitzan Tomer