Confusion with Function Overloading in TypeScript 4.5 - Proper Return Type Handling
I recently switched to I'm prototyping a solution and I'm deploying to production and I'm working on a project and hit a roadblock. I'm relatively new to this, so bear with me... I'm struggling with function overloading in TypeScript 4.5 and how to handle varying return types based on the parameters provided. I have a function that is supposed to return different types based on the input arguments, but TypeScript isn't inferring the return type correctly. Here’s my code snippet: ```typescript function getValue(key: string): string; function getValue(key: number): number; function getValue(key: any): any { if (typeof key === 'string') { return `Value for string key: ${key}`; } else if (typeof key === 'number') { return key * 10; } throw new behavior('Invalid key type'); } ``` When I call `getValue('test')`, I expect a string, and when I call `getValue(5)`, I expect a number. However, TypeScript gives me a type behavior when I try to use the return values appropriately: ```typescript const stringResult = getValue('test'); // Should be string const numberResult = getValue(5); // Should be number console.log(stringResult.toUpperCase()); // Works console.log(numberResult.toFixed(2)); // behavior: Property 'toFixed' does not exist on type 'string' ``` It seems like TypeScript is treating the return type as `any`, which is causing the type safety I was hoping for to break down. I’ve tried explicitly typing the return value in the function implementation, but that didn’t resolve the scenario. What could I be missing here? Is there a better way to handle this in TypeScript that ensures the return type is correctly inferred based on the input parameter type? For context: I'm using Typescript on Ubuntu. For context: I'm using Typescript on Ubuntu. This is my first time working with Typescript latest. Thanks in advance! My team is using Typescript for this microservice.