How to use reduce Method In Typescript

Using the for…in loop

This approach employs a functional programming style with TypeScript’s reduce method. It iterates over the keys of the original dictionary, selectively adding key-value pairs to the filtered dictionary based on specified conditions.

Syntax:

const filteredDictionary = Object.keys(originalDictionary).reduce((acc, key) => {
    if (typeof originalDictionary[key] === 'string') {
        acc[key] = originalDictionary[key];
    }
    return acc;
}, {} as Record<string, any>);

Example:

JavaScript

const originalDictionary: Record<string, any> = {
    name: 'w3wiki',
    est: 2009,
    city: 'Noida'
};

const filteredDictionary = Object.keys(originalDictionary).reduce((acc, key) => {
    if (typeof originalDictionary[key] === 'string') {
        acc[key] = originalDictionary[key];
    }
    return acc;
}, {} as Record<string, any>);

console.log(filteredDictionary);

Output:

{
    name: "w3wiki",
    city: "Noida"
}

Filter a Dictionary by Key or Value in TypeScript

Filtering a dictionary by key or value is a common task in TypeScript when working with data structures. TypeScript provides various approaches to achieve this efficiently.