Understanding how to extract an enum from a string and its corresponding value in TypeScript

Question

Understanding how to extract an enum from a string and its corresponding value in TypeScript

I am working with a simple enum called errorCode, shown below:

export enum SomeErrorCodes {
    none = 0,
    notFound = 1,
    duplicated = 2
}

Currently, I am receiving the name of the enum as a string "SomeErrorCodes" and a number, for example, 1. How can I convert these into SomeErrorCodes.notFound in TypeScript?

Appreciate any help!

typescript enums

Answer 1

Answer №1

Your enumeration will be converted into

Object
0: "none"
1: "notFound"
2: "duplicated"
duplicated: 2
none: 0
notFound: 1

This allows you to easily retrieve a value by its corresponding key,

function getErrorCode(code: number): string {
  return SomeErrorCodes[code] || 'Code does not exist';
}

Answer 2

Your enumeration will be converted into

Object
0: "none"
1: "notFound"
2: "duplicated"
duplicated: 2
none: 0
notFound: 1

This allows you to easily retrieve a value by its corresponding key,

function getErrorCode(code: number): string {
  return SomeErrorCodes[code] || 'Code does not exist';
}

Answer 3

Answer №2

To access the key name and retrieve the corresponding enum, you can utilize Object.keys method followed by mapping to the appropriate enum. Check out the working solution on https://www.typescriptlang.org/play/index.html for a complete understanding:

enum Fruits {
    Apple = 1,
    Orange
}

enum Vegetables {
    Carrot = 75,
    Lettuce = 88,
    Asparagus = 96
}

class CustomParser {
    public GetValues(dataObject: any): string[] {
        const customStrings: string[] = [];
        const firstKey = Object.keys(dataObject)[0];

        let fetchStringMethod: (value: number) => string;

        switch (firstKey) {
            case "Fruits":
                fetchStringMethod = (fruit: number) => {
                    return Fruits[fruit];
                }
                break;
            case "Vegetables":
                fetchStringMethod = (veg: number) => {
                    return Vegetables[veg];
                }
                break;
            default:
                throw "Unknown enum...";
        }

        const integerValues = (<string>dataObject[firstKey]).split(",")
            .map(x => Number.parseInt(x.trim()));


        for (const intValue of integerValues) {
            customStrings.push(fetchStringMethod(intValue));
        }

        return customStrings;
    }
}

const customParser = new CustomParser();
let fruitsElement = document.createElement('h2');
fruitsElement.textContent = customParser.GetValues({ "Fruits": "1,2" }).join(", ");
document.body.appendChild(fruitsElement);
let veggiesElement = document.createElement('h2');
veggiesElement.textContent = customParser.GetValues({ "Vegetables": "88" }).join(", ");
document.body.appendChild(veggiesElement);

Answer 4

To access the key name and retrieve the corresponding enum, you can utilize Object.keys method followed by mapping to the appropriate enum. Check out the working solution on https://www.typescriptlang.org/play/index.html for a complete understanding:

enum Fruits {
    Apple = 1,
    Orange
}

enum Vegetables {
    Carrot = 75,
    Lettuce = 88,
    Asparagus = 96
}

class CustomParser {
    public GetValues(dataObject: any): string[] {
        const customStrings: string[] = [];
        const firstKey = Object.keys(dataObject)[0];

        let fetchStringMethod: (value: number) => string;

        switch (firstKey) {
            case "Fruits":
                fetchStringMethod = (fruit: number) => {
                    return Fruits[fruit];
                }
                break;
            case "Vegetables":
                fetchStringMethod = (veg: number) => {
                    return Vegetables[veg];
                }
                break;
            default:
                throw "Unknown enum...";
        }

        const integerValues = (<string>dataObject[firstKey]).split(",")
            .map(x => Number.parseInt(x.trim()));


        for (const intValue of integerValues) {
            customStrings.push(fetchStringMethod(intValue));
        }

        return customStrings;
    }
}

const customParser = new CustomParser();
let fruitsElement = document.createElement('h2');
fruitsElement.textContent = customParser.GetValues({ "Fruits": "1,2" }).join(", ");
document.body.appendChild(fruitsElement);
let veggiesElement = document.createElement('h2');
veggiesElement.textContent = customParser.GetValues({ "Vegetables": "88" }).join(", ");
document.body.appendChild(veggiesElement);

Understanding how to extract an enum from a string and its corresponding value in TypeScript

Answer №1

Answer №2

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