Typescript complex class-CodePudding

I'm trying to fill class in typescript. But error 2779.

error TS2779: The left-hand side of an assignment expression may not be an optional property access.

Class

export class SendEmail {
    sender?: ISender
}
interface ISender {
    name: string
    email: string
}

Declaration. Here I try fill my class.

let mail: SendEmail = new SendEmail();

mail.sender?.email = "[email protected]";   //<= error TS2779 here . If I try mail.sender!.email = "[email protected]", I have message Cannot set properties of undefined;
mail.sender?.name = "John Doe"

It's a simple example. I will have to fill in much larger class with subsub interface.

Thank you for help. I'm beginner in TS.

CodePudding user response：

The ?. operator is not supported on the left hand side of an assignment (this is a JavaScript limitation)

You need to check for the sender before you assign it's fields:


if (mail.sender) {
    mail.sender.email = "[email protected]";   
    mail.sender.name = "John Doe"
}

Playground Link

Although you might be better off actually assigning the sender and creating a new object:


mail.sender ={
    email: "[email protected]",
    name: "John Doe"
}

Playground Link