typescript 即使属性未标记为只读，打字稿“无法分配给属性，因为它是常量或只读的”
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Typescript "Cannot assign to property, because it is a constant or read-only" even though property is not marked readonly
提问by Hentov
I have the following code
我有以下代码
type SetupProps = {
defaults: string;
}
export class Setup extends React.Component<SetupProps, SetupState> {
constructor(props: any) {
super(props);
this.props.defaults = "Whatever";
}
When trying to run this code the TS compiler returns the following error:
尝试运行此代码时，TS 编译器返回以下错误：
Cannot assign to 'defaults' because it is a constant or a read-only property.
无法分配给“默认值”，因为它是一个常量或只读属性。
How is deafualtsa readonly property, when its clearly not marked this way.
deafualts只读属性如何，当它明确没有以这种方式标记时。
采纳答案by Aleksey L.
You're extending React.Componentand it defines propsas Readonly<SetupProps>
你正在扩展React.Component，它定义props为Readonly<SetupProps>
class Component<P, S> {
constructor(props: P, context?: any);
...
props: Readonly<{ children?: ReactNode }> & Readonly<P>;
state: Readonly<S>;
...
}
If you want to assign some default values, you can go with something like:
如果要分配一些默认值，可以使用以下内容：
constructor({ defaults = 'Whatever' }: Partial<SetupProps>) {
super({defaults});
}
