Encapsulating constructor variables in TypeScript classes through private access modifiers and using public getters

Question

Encapsulating constructor variables in TypeScript classes through private access modifiers and using public getters

Coming from a background in C#, I am used to designing most of my classes to be immutable. I am curious about whether it is considered good practice in TypeScript to use private constructor variables and public getters for accessing data within classes.

Take this example:

class UnitType {
   constructor(private code: string, private name: string, private unitType: string) {

}

get Code(): string {
    return this.code;
}
get Name(): string {
    return this.name;
}
get UnitType(): string
    return this.unitType;
}

I have not been able to find many examples of TypeScript code structured like the one above. Is there something that I am overlooking?

typescript angular immutability

Answer 1

Answer №1

Indeed, practicing encapsulation is highly beneficial. It helps reduce potential errors and simplifies the mental workload for programmers by limiting the scope of variables that need to be managed.

While it is possible to simulate private properties in ES5, it often leads to complex and less readable code. This can also impact performance negatively. Therefore, it is uncommon to come across such implementations in JavaScript due to the absence of built-in private modifiers.

It is important to note that in TypeScript, properties marked as private are only enforced at compile-time. At runtime, when the code is executed as JavaScript, these "private" properties remain accessible despite their designation.

Answer 2

Indeed, practicing encapsulation is highly beneficial. It helps reduce potential errors and simplifies the mental workload for programmers by limiting the scope of variables that need to be managed.

While it is possible to simulate private properties in ES5, it often leads to complex and less readable code. This can also impact performance negatively. Therefore, it is uncommon to come across such implementations in JavaScript due to the absence of built-in private modifiers.

It is important to note that in TypeScript, properties marked as private are only enforced at compile-time. At runtime, when the code is executed as JavaScript, these "private" properties remain accessible despite their designation.

Answer 3

Answer №2

If you want to streamline your class, simply use the public readonly keyword like this:

class UnitType {
    constructor(
        public readonly code: string, 
        public readonly name: string, 
        public readonly unitType: string) {
    }
}

// Example:
var type1 = new UnitType("a", "b", "c");

// This will result in an error TS2450: Left-hand side of assignment expression cannot be a constant or a read-only property.
type1.code = "aa";

Answer 4

If you want to streamline your class, simply use the public readonly keyword like this:

class UnitType {
    constructor(
        public readonly code: string, 
        public readonly name: string, 
        public readonly unitType: string) {
    }
}

// Example:
var type1 = new UnitType("a", "b", "c");

// This will result in an error TS2450: Left-hand side of assignment expression cannot be a constant or a read-only property.
type1.code = "aa";

Encapsulating constructor variables in TypeScript classes through private access modifiers and using public getters

Answer №1

Answer №2

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