rswitch

rswitch

The rswitch library provides a flexible and compact way to implement switch-like functionality in TypeScript. It allows you to define cases and their corresponding actions using object literals or arrays. This version includes both synchronous and asynchronous handling of cases and actions.

Installation

To install the rswitch library, use the following npm command:

npm install rswitch

Usage

The rswitch function evaluates a given key against predefined cases and returns the corresponding action. There are two versions of this function available:

• Synchronous version: rswitch – works for synchronous operations.
• Asynchronous version: rswitchAsync – works for cases where the action is asynchronous (i.e., it returns a Promise).

Syntax

rswitch(key: string | number | undefined | null, casesObj: RSwitch, options?: Options): T | undefined;

rswitchAsync(key: string | number | undefined | null, casesObj: RSwitch, options?: Options): Promise<T | undefined>;

• key: The value to evaluate against the cases (can be a string, number, undefined, or null).
• casesObj: An object or an array of key-value pairs defining the cases and their corresponding actions.
• options (optional): Configuration options to customize the behavior of the rswitch function.
  • callFn (optional, default: true): If set to true, the function will call actions that are functions and return their result. If set to false, the function will return the function itself without calling it.

Example Usage

Synchronous rswitch Example

import rswitch from "rswitch";
// const {rswitch} = require("rswitch") // commonjs

// Example usage of rswitch (synchronous)
const result = rswitch("dev", {
  designer: "Designer",
  "dev, web": "Developer",
  "": "No match found", // Default case
});

console.log(result); // Output: "Developer"

Asynchronous rswitchAsync Example

import { rswitchAsync } from "rswitch";
// const {rswitchAsync} = require("rswitch") // commonjs

// Example usage of rswitchAsync (asynchronous)
async function testAsyncSwitch() {
  const result = await rswitchAsync("web", {
    "dev, web": async () => {
      return "Developer"; // Async case
    },
    designer: "Designer",
    "": "No match found", // Default case
  });

  console.log(result); // Output: "Developer" (async case)
}

testAsyncSwitch();

Case Definitions

Cases are defined as key-value pairs within the casesObj. Here’s how you can define various cases:

• Single Case: Use a direct key-value pair for a single match.

  { 'dev': 'Developer' }
  

• Multiple Cases: You can group several cases together in one key, separated by commas (,), and the key will match any of those cases.

  { 'dev, web': 'Developer' }
  

• Default Case: The empty string key ("") can be used for the default case, which is executed when no other key matches.

  { '': 'No match found' }
  

Actions

Actions can be:

• Primitive values (e.g., strings, numbers, booleans).
• Functions: If the action is a function, it will be executed. If the function returns a Promise, it will be awaited.

Function Actions:

If the action is a function:

• Synchronous: The function will be called and its result will be returned.

• Asynchronous: The function will return a Promise, which will be resolved before returning the result.

  If options.callFn is set to false, the function will not be invoked, and the function itself will be returned.

Handling Undefined or Null Keys

If rcase is undefined or null, and no default case ("") is defined in casesObj, the function will return undefined. If a default case is defined, it will return the value of the default case.

Full Example with Multiple Cases

import rswitch, { rswitchAsync } from "rswitch";
// const { rswitch, rswitchAsync } = require("rswitch"); // commonjs

const result1 = rswitch("web", {
  "dev, web": "Developer",
  designer: "Designer",
  "": "No match found", // Default case
});

console.log("sync", result1); // Output: "Developer"

async function testAsyncSwitch() {
  const result2 = await rswitchAsync("web", {
    "dev, web": async () => {
      return "Developer"; // Async case
    },
    designer: "Designer",
    "": "No match found", // Default case
  });

  console.log("async", result2); // Output: "Developer" (async case)
}

testAsyncSwitch();

Notes

• Multiple Cases for One Action: You can define one action for multiple cases by separating the case names with commas in a string, like 'dev, web'.
• Default Case: The "" key is treated as the default case, executed when no other match is found.
• Type Safety: TypeScript will provide type safety when using rswitch, ensuring that the provided key, casesObj, and options match expected types.

Contributing

We welcome contributions to the rswitch library! If you find any issues or want to add new features, please fork the repository and submit a pull request.