ES5 Promises & Error Handling

index.tpl.html

<div id="output">
</div>

test.js

/*
	The purpose of this fiddle is to showcase the
  power of ES5's Promise Async function using
  try/catch/finally to do error handling, the
  Array.reduce function to filter and recompile an
  object (note the illegal use of Array as object),
  and also the chaining method of the new Promise function.
  
  You must wait 4 seconds for anything to happen!!!!!!!
  You are likely to get errors due to the isTrue and
  rejectIt variables being true/false
*/
  
// Primary Dom Element
var output = document.getElementById('output');
// Temporary Empty Var To Use As Ref
var results;
// Fake Conditions
// isTrue will run as a conditional argument
var isTrue = false;
// rejectIt will determine whether to resolve or 
// reject the promise
var rejectIt = false;
// Empty Array Var
var arr;
// Define a promise object;
var promise = new Promise(function(resolve, reject) {
  setTimeout(function() {
    arr = [{
      user: 'Ray',
      age: 28
    }, {
      user: 'Jeff',
      age: 32
    }, {
      user: 'Court',
      age: 50
    }];
    // Try a condition
		try {
    		// If It's True, resolve the data immediately
    		if (isTrue) null;
        // If It's False, throw an error to the 
        // Catch statement. It's object is (e)
			  else throw new Error("There's Been An Error");
    } catch (e) {
    		// Log the Error to Console for Client to See
    		console.error(e.message, e);
        // Don't Reject The Error here
        // reject({message: "Not True Man", arr});
    } finally {
    	// Determine whether we should reject the array
      // based on some other predetermined condition
      // Here we use the fake rejectIt boolean
      // If it's true, we halt the compiler and go no further
      if (rejectIt) reject({message: "Not True Man", arr});
      // If RejectIt is false, lets send the 
      // arr into the next .then function by
      // resolving it
      else resolve(arr);
    }
	// Wait Some amount of time
  // Before we fire this function
  }, 4000)
});
// Step 2 of the promise
promise.then(function(resultsOfLastStep) {
	// We Create a User Variable to hold our
  // Results of the reduce function.
  // resultsOfLast Step is the object inside of
  // the resolve function resolve('I Am resultOfLastStep');
  var User = resultsOfLastStep.reduce(function(emptyArray, currentIteration, i, a) {
  	// Some Arbitrary condition
    // Notice that we are illegally combining
    // Object.Keys with an [array] notation
    if (currentIteration.user === 'Jeff') emptyArray.objectInArrNumberOne = currentIteration;
    // Some other Arbitrary condition
    // Same illegal combination of objects and arrays
    else if (currentIteration.user === 'Ray') emptyArray.objectInArrNumberTwo = currentIteration
    // Some Last Arbitrary condition
    // Push the entire currently iterated
    // object into the empty array from the end of
    // this function
    if (currentIteration.age >= 30) emptyArray.push(currentIteration);
    // Make sure we return the empty array so that
    // Each consecutive iteration of the reduce function
    // It adds new data to this array node
    return emptyArray;
  }, []);
  // Set Empty Results Var to User;
  return results = User;
});
// Step 3 of the promise
promise.then(function(nextStep){
	// nextStep === User <-- returned value of last function
	// Output to the Primary DOM Element
  output.innerHTML = 	JSON.stringify(results);
	// Simple Console log on the output data
  console.log(["Data in the Output Div", output], 
  ["User Object", results], ['Next Step Resolved Object', nextStep]);
 // We'll try a fake try catch block
  try {
  	// Let's determine if the isTrue boolean is set
    // If it's true, just log to the console
  	if (isTrue) console.warn("Yay! Its True");
    // If it's false, manually tell the compiler
    // that we have an error
    else throw new Error("You've Got Errors Mang");
  } catch (e) {
  	// This Catch block will do something with
    // The error we threw in the last step
    // Just console.logs the error's message and the
    // entire stack trace for better error handling
  	console.error({message: e.message, error: e});
  } finally {
  	// Finally, we do something regardless
    // of if the previous try/catch failed or passed
  	console.info("Just Going with the Flow", ['User Object Again', results]);
  }
});