I have an interface with the following:
interface orderItem { symbol: string, side: string, price: number quantity: number } I want to create an array "orders" consisting of "orderItems" in my constructor.
However, orders : [orderItem] doesn't seem to be doing the trick. Does anyone know how I can proceed?
Here is what I am trying to do in my constructor:
this.state = { orders: orderItem [] } Since you're doing an object literal, the colon is used to divide the key from the value (ie, it has its normal javascript meaning, not its typescript meaning). As a result, trying to set the type the way you're doing is causing an error.
There are a few ways you could do what you want. You could set the type using the as keyword:
this.state = { orders: undefined as orderItem[] }; or with an empty array:
this.state = { orders: [] as orderItem[] }; Or you could create something ahead of time, and then insert that into the object:
let myOrders: orderItem[] = []; this.state = { orders: myOrders }; Or you could have a separate interface for the state and use that:
interface myState { orders: orderItem[] } class myClass { private state: myState; constructor () { this.state = { orders: undefined } } } 
What you want is this:
this.orders = new Array<orderItem>(); You need to declare it like this:
interface CartState extends Object { orders: OrderItem[] } class Cart { private state: CartState; constructor(orders: OrderItem[]) { this.state = { orders }; } } Typescript documentation for declaring arrays.
