Is there a different term I can use instead of 'any' when specifying an object type in Typescript?

class ResistorColor 
{
  private colors: string[]

  public colorValues: {grey: number, white: number} = {
    grey: 8,
    white: 9
  }
}

We can replace 'any' with a specific type to ensure proper typing in Typescript. How do we assign correct types to objects like this in Typescript?

Answer №1

It is advisable to avoid using the any type unless absolutely necessary. By defining a variable as any, TypeScript loses the ability to enforce typing rules, leading to potential misuse of the variable.

A better approach would be to define custom types for specific scenarios. For example, you can create a type Color that represents all valid color names as strings. Then, use this type to strongly type your variables such as private colors: Color[] and

public colorValues: Record<Color, number>
.

type Color = 'grey' | 'white';

class ResistorColor 
{
  private colors: Color[] = [];

  public colorValues: Record<Color, number> = {
    grey: 8,
    white: 9
  }
}

Check out an example in Typescript Playground

If you need to dynamically generate the type Colors based on an array of color names, consider using the typeof operator. This method allows you to derive the type from existing data sets and ensure type safety throughout your codebase.

const colors = ['grey', 'white'] as const;

type Color = (typeof colors)[number];

class ResistorColor {
    public colorValues: Record<Color, number>;

    constructor(baseVal: number = 0) {
        this.colorValues = {} as Record<Color, number>;
        colors.forEach(
            color => this.colorValues[color] = baseVal
        );
    }
}

Explore the code snippet in Typescript Playground

Answer №2

It has been noted by other contributors that using the any type annotation in TypeScript does not necessarily contribute to writing secure code. In such cases, it is advisable to omit the type annotation and rely on TypeScript's ability to infer types through Type Inference.

If there is a need for an explicit type annotation for the variable colorValues, one approach could be to define an interface that outlines the expected properties of the object.

interface Colors {
  grey: number;
  white: number;
}

public colorValues: Colors = {
  grey: 8,
  white: 9
}

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