Instantiating a Class in TypeScript

Question

I have the following class structure

module ChartingServices {

export class ChartOptions {
    options: myOptions;
    title: string;
}

export interface myOptions {
    colors: string[];
    legend: myLegend;
    type: string;
}

export interface myLegend{
    enabled: boolean;
    labelFormatter: string;
}
}

and I create an instance of it in the usual way:-

var chartOptions = new ChartingServices.ChartOptions();

I can set the property chartOptions.title with no problem at all.

However, I cannot get to the property chartOptions.myOptions.type and get an error about not being able to read property 'type' of undefined.

Bearing in mind I have loads of classes, do I need to create an instance of each one to set / read properties. What can I do to get the code to work?

Answer 1

The first problem is that .myOptions does not exist on chartOptions - you want options. You should capitalize all of your types: MyOptions, MyLegend, so that you do not confuse them with property names.

The second problem is that although you instantiate a new ChartOptions:

var chartOptions = new ChartOptions();

...its options property isn't actually set to anything, and is therefore undefined. You need to set it either using a statement right after instantiation:

chartOptions.options = {type: "foo", ...other non-optional properties here}

Or in the constructor of ChartOptions, or via:

options: MyOptions = {type: "foo", ...}