How to compute the sum and average of elements in an array?

Empty arrays: Check yourself before you wreck yourself

With empty arrays, performing a check is crucial to avert disaster:

const nums = [];
// make sure you invite someone before throwing a party!
const sum = nums.reduce((a, b) => a + b, 0);
const avg = nums.length ? sum / nums.length : 0;
console.log(`Sum: ${sum}, Avg: ${avg}`);


Strings disguised as numbers? Not on my watch!

Ensure proper computation by turning strings back to their true number self:

const nums = ["1", "2", "3", "4", "5"];
// the old switcheroo
const sum = nums.reduce((a, b) => a + parseInt(b, 10), 0);
const avg = sum / nums.length;
console.log(`Sum: ${sum}, Avg: ${avg}`);


Enhancements for real programmers

Here are some tips and tricks to get your code running smoother than a buttered weasel.

Show off your results with document.write()

document.write() - because user-facing outputs like a bit of flair:

document.write(`Sum: ${sum}, Avg: ${avg}`);


Reusable code? Yes please!

Put your logic inside a function for easy access everywhere:

function calculateSumAndAverage(array) {
    const sum = array.reduce((a, b) => a + parseInt(b, 10), 0);
    const avg = array.length ? sum / array.length : 0;
    return { sum, avg };
}

const results = calculateSumAndAverage(nums);
console.log(`Sum: ${results.sum}, Avg: ${results.avg}`);


Keep it short and sweet with ES6 arrow functions

ES6 arrow functions - less writing, more coding:

const calculateSumAndAverage = (array) => {
    const sum = array.reduce((a, b) => a + parseInt(b, 10), 0);
    const avg = array.length ? sum / array.length : 0;
    return { sum, avg };
};


Expand your horizon

Large numbers: The bigger they come...

For arrays biggger than Godzilla, consider the performance of reduce() versus old school loops.

Beware of floats!

In JavaScript, decimal numbers might bite! Let's tame them:

const nums = [0.1, 0.2, 0.3];
// Be precise! Like a cat jumping onto a tiny shelf.
const sum = nums.reduce((a, b) => a + b, 0).toFixed(2);
const avg = (sum / nums.length).toFixed(2);
console.log(`Sum: ${sum}, Avg: ${avg}`);


Modern JavaScript: Stay ahead of the game

Empower your code with spread syntax for one step ahead operations:

const sum = [...nums].reduce((a, b) => a + b, 0);
const avg = sum / nums.length;


Asynchronous data: Keep promises

Async data? No worries, use Promises or async/await with array-pleasing methods.