Exception free JavaScript?

avoiding-exceptions.js

/**
 * WHY? - BECAUSE EXCEPTIONS/TRY/CATCH IS A GLOBAL HORRIBLE MESS :-(
 * Check out error handling in golang: https://blog.golang.org/error-handling-and-go
 */

/**
 * Wrap an "unsafe" promise
 */
function safePromise(promise) {
  return promise
  .then(result => [null, result])
  .catch(error => [error, null]);
}

/**
 * Wrap an "unsafe" function that might throw
 * upon execution in a function that returns
 * a promise (which is handled "safely" with safePromise)
 *
 * NOTE: This will only handle throws that
 * are done within the same execution tick,
 * and not errors that are thrown "later"
 * within the same context (no way to do that..)
 */
function safeFunction(fn) {
  return function(...args) {
    let error = null;
    let result = null;

    try {
      result = fn.apply(this, args);
    } catch (e) {
      error = e;
    }

    return safePromise(error ? Promise.reject(error) : Promise.resolve(result));
  }
}

/**
 * Example of promise returning function that rejects
 */
function getAsset(id) {
  return Promise.reject(new Error('Booo!'));
}

/**
 * Example use with async/await
 */
async function letsDoThis() {
  // Alt 1 (wrapping a promise returning function)
  const [error, result] = await safeFunction(getAsset)(10);
  // Alt 2 (wrapping a promise)
  const [error, result] = await safePromise(getAsset(10));
  
  if (error) {
    /**
     * Handle the error appropriately
     * (You could of course just throw it here if you wanted to - but it is at least optional)
     */
  }
  
  //...
}