The value of 'Boolean' cannot be changed as it is a constant or a read-only property and cannot be assigned

Question

The value of 'Boolean' cannot be changed as it is a constant or a read-only property and cannot be assigned

I've been working on creating a TypeScript object to handle read/write permissions in my application, but I'm stuck on an issue with variable assignment that doesn't make sense to me. Any help or guidance would be greatly appreciated.

export class Permission {
       watcher: Object = { read: Boolean = true };
}

When I try to use the code above, I get this error message:

[ts] Cannot assign to 'Boolean' because it is a constant or a read-only property. const Boolean: BooleanConstructor

I have a feeling I'm missing something simple here, so please forgive me if this is a basic mistake.

typescript

Answer 1

Answer №1

If you meant to define your observer attribute as an object with the property view, it should have a structure like this:

export class AccessControl {
  // The part after the ":" represents the type of the property.
  // The part after "=" is its default value
  observer: { 
    view: boolean
  } = { view: true };
}

The current syntax might result in an error. It seems like you don't want to replace the built-in constructor Boolean with Boolean = true.

Answer 2

If you meant to define your observer attribute as an object with the property view, it should have a structure like this:

export class AccessControl {
  // The part after the ":" represents the type of the property.
  // The part after "=" is its default value
  observer: { 
    view: boolean
  } = { view: true };
}

The current syntax might result in an error. It seems like you don't want to replace the built-in constructor Boolean with Boolean = true.

Answer 3

Answer №2

Attempting to assign a JSON object with { read: true }, stating it as type Boolean is unnecessary (as true and false are always Boolean). TypeScript can infer the type, resulting in an invalid JSON configuration.

The correct format for JSON is:

{
  key: value,
  key2: value2
}

Note that there are no equal signs (=) in JSON, only colons : to distinguish between keys and values.

It seems that the use of the class syntax might be causing confusion because it includes an equal sign for assignment. However, after assigning a value, you should not include an equals sign.

Your finalized class definition should resemble something like this:

export class Permission {
    watcher = { read: true };
}

For more complex objects, interfaces would be necessary if you require optional variables or have dependencies on other objects. For simple objects, TypeScript will interpret the structure based on the types provided.

Answer 4

Attempting to assign a JSON object with { read: true }, stating it as type Boolean is unnecessary (as true and false are always Boolean). TypeScript can infer the type, resulting in an invalid JSON configuration.

The correct format for JSON is:

{
  key: value,
  key2: value2
}

Note that there are no equal signs (=) in JSON, only colons : to distinguish between keys and values.

It seems that the use of the class syntax might be causing confusion because it includes an equal sign for assignment. However, after assigning a value, you should not include an equals sign.

Your finalized class definition should resemble something like this:

export class Permission {
    watcher = { read: true };
}

For more complex objects, interfaces would be necessary if you require optional variables or have dependencies on other objects. For simple objects, TypeScript will interpret the structure based on the types provided.

The value of 'Boolean' cannot be changed as it is a constant or a read-only property and cannot be assigned

Answer №1

Answer №2

Similar questions

The property is accessed prior to being initialized

The NestJs provider fails to inject and throws an error stating that this.iGalleryRepository.addImage is not a recognized function

Ensuring the correct type for an object's interface property value

Using TypeScript to define generic types for classes, method parameters, and method return types

Getting the Most Out of .find() in Angular 4

Create a function that will always output an array with the same number of elements as the input

Unable to fake a fetch request using the 'fetch-mock-jest 1.5.1' library

What is the best way to choose a particular radio button from a group of radio buttons using typescript?

Angular2 data binding does not update when properties change

"Implementing self-referencing mongoose models in Typescript: A step-by-step guide

Determine the `overall` amount and adjust `overall` to equal `quantity * price` within a Typescript

Encountering a 405 HTTP error in Angular8 app when refreshing the page

Employing square bracket notation based on the input data

Steps to retrieve the final page number from ngx-pagination with Angular

What is the reason behind taps in TypeScript only registering the first tap event?

Angular 8 encountered a 404 (Not Found) error when trying to POST to http://localhost:4200/assets/data/students.json

Real-time webpage updates with Spring Boot, Typescript, and IntelliJ

When comparing TypeScript class functions with regular functions and variables, which one yields better performance?

Tips for targeting a specific element with providers in Ionic

What is the best way to invoke a function in a class from a different class in Angular 6?