Using TypeScript with React: Initializing State in the Constructor

Question

Using TypeScript with React: Initializing State in the Constructor

Within my TypeScript React App, I have a long form that needs to dynamically hide/show or enable/disable elements based on the value of the status.

export interface IState {
  Status: string;
  DisableBasicForm: boolean;
  DisableFeedbackCtrl: boolean;
  DisableTypeofReqCtrl: boolean;
  DisablePurposeCtrl: boolean;
  DisableDutyStation: boolean;
  DisableContractManager: boolean;
  ...
}

In the class constructor, I need to initialize the State. What is the best way to do this without individually initializing each variable present in IState?

public constructor(props: IGoodsProps) {
    super(props);
//Looking for minimal code required here.
}

javascript typescript spfx

Answer 1

Answer №1

If you're fine with some properties having a default value of undefined, you can designate them as optional in the IState interface by adding a ?. For instance, here's an example (selected randomly since your requirements are not known):

export interface IState {
  Status: string; // mandatory property
  DisableBasicForm?: boolean; // optional property
  DisableFeedbackCtrl?: boolean;
  // ...
}

You can leave out the optional properties when initializing the state in the constructor.

Which properties should be optional? If you want any booleans to default to false, using undefined may suffice because in JavaScript, undefined is considered "falsey". (let me know if you need more clarification on this)

Answer 2

If you're fine with some properties having a default value of undefined, you can designate them as optional in the IState interface by adding a ?. For instance, here's an example (selected randomly since your requirements are not known):

export interface IState {
  Status: string; // mandatory property
  DisableBasicForm?: boolean; // optional property
  DisableFeedbackCtrl?: boolean;
  // ...
}

You can leave out the optional properties when initializing the state in the constructor.

Which properties should be optional? If you want any booleans to default to false, using undefined may suffice because in JavaScript, undefined is considered "falsey". (let me know if you need more clarification on this)

Answer 3

Answer №2

When implementing IState, it is necessary to initialize each property of IState since they are not marked as optional.

For example:

public constructor(props: IGoodsProps) {
    const {status} = this.props
     super(props);
     this.state ={
       Status: status,
       DisableBasicForm: status.Status === 'yourValue',
       ... // initialization here
    } 
}

If you have a default value for your state passed as a prop, you can use object destructuring:

public constructor(props: IGoodsProps) {
    const {status} = this.props
     super(props);
     this.state ={
       ...status,
       DisableBasicForm: status.Status === 'yourValue', // overwrite this property with your logic
    } 
}

You can also initialize your state outside the constructor:

class Component extends React.Component<Props, State> {
  state: State = {
    Status: 'value',
    ... // initialization here
  }

  constructor(props: Props) {
   ...
  }

If you have shared logic for setting your state and want to avoid repetition, consider using React.useState but your component needs to be a function.

Answer 4

When implementing IState, it is necessary to initialize each property of IState since they are not marked as optional.

For example:

public constructor(props: IGoodsProps) {
    const {status} = this.props
     super(props);
     this.state ={
       Status: status,
       DisableBasicForm: status.Status === 'yourValue',
       ... // initialization here
    } 
}

If you have a default value for your state passed as a prop, you can use object destructuring:

public constructor(props: IGoodsProps) {
    const {status} = this.props
     super(props);
     this.state ={
       ...status,
       DisableBasicForm: status.Status === 'yourValue', // overwrite this property with your logic
    } 
}

You can also initialize your state outside the constructor:

class Component extends React.Component<Props, State> {
  state: State = {
    Status: 'value',
    ... // initialization here
  }

  constructor(props: Props) {
   ...
  }

If you have shared logic for setting your state and want to avoid repetition, consider using React.useState but your component needs to be a function.

Using TypeScript with React: Initializing State in the Constructor

Answer №1

Answer №2

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