how to extend interface/class on variable declaration

Question

How do I extend an interface or class on variable declaration?

For example:

export declare abstract class DynamicFormControlModel implements DynamicPathable {
    asyncValidators: DynamicValidatorsConfig | null;
    _disabled: boolean;
    disabledUpdates: Subject<boolean>;
    errorMessages: DynamicValidatorsConfig | null;
    hidden: boolean;
    id: string;
    label: string | null;
    labelTooltip: string | null;
    controlTooltip: string | null;
    layout: DynamicFormControlLayout | null;
    name: string;
    parent: DynamicPathable | null;
    relation: DynamicFormControlRelationGroup[];
    updateOn: FormHooks | null;
    validators: DynamicValidatorsConfig | null;
    abstract readonly type: string;
    protected constructor(config: DynamicFormControlModelConfig, layout?: DynamicFormControlLayout | null);
    disabled: boolean;
    readonly hasErrorMessages: boolean;
    toJSON(): Object;
}

model: DynamicFormControlModel extend {value:string}

model: DynamicFormControlModel extend {value:string} returns error
I know I could extend {value: string} or include "value" on the class itself, but I'm not looking for this answer.

Matt McCutchen · Accepted Answer · 2018-09-24 03:14:57Z

1

You can use an intersection type:

let model: DynamicFormControlModel & {value:string};

answered Sep 24, 2018 at 3:14

Matt McCutchen

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1 Comment

nicker Over a year ago

Hi @MattMcCutchen, thanks for your answer. i'd been searching for an hour and your answer solve my issue.

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