Recap: Advanced Type Combos

Part of the Introduction To TypeScript section of Coddy's JavaScript journey — lesson 36 of 73.

Challenge

Easy

Create a type alias named Success for an object with a status property of literal type "success" and a data property of type any.

Create a type alias named Failure for an object with a status property of literal type "error" and a message property of type string.

Create a type alias named Result that is a union of the Success and Failure types.

Create a function named processResult that accepts a parameter called result of type Result and returns a string. The function should use a type guard on the status property to determine the result type and behave as follows:

If the status is "success", return "Operation successful: [data]"
If the status is "error", return "Operation failed: [message]"

Create another function named handleApiResponse that accepts a parameter called response of type Result and returns a boolean. The function should return true if the operation was successful and false if it failed.

The following inputs will be provided:

First input: a JSON string representing either a success result like {"status": "success", "data": "User created"} or a failure result like {"status": "error", "message": "Invalid credentials"}
Second input: another JSON string in the same format

Parse both JSON inputs as Result objects, then:

Call processResult with the first parsed result and print the returned string
Call handleApiResponse with the first parsed result and print the returned boolean
Call processResult with the second parsed result and print the returned string
Call handleApiResponse with the second parsed result and print the returned boolean

Try it yourself

import * as readline from 'readline';

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

const input: string[] = [];

// TODO: Write your code here
// 1. Create type aliases for Success, Failure, and Result

// 2. Create the processResult function

// 3. Create the handleApiResponse function

rl.on('line', (line: string) => {
    input.push(line.trim());
    if (input.length === 2) {
        // Parse the JSON inputs
        const result1 = JSON.parse(input[0]);
        const result2 = JSON.parse(input[1]);
        
        // 4. Call the functions with the parsed results and print the outputs
        
        
        rl.close();
    }
});

Recap: Advanced Type Combos

All lessons in Introduction To TypeScript