Array Average

Program to calculate average of array elements

BeginnerTopic: Array Programs

JavaScript Array Average Program

This program helps you to learn the fundamental structure and syntax of JavaScript programming.

// Method 1: Using for loop
function averageLoop(arr) {
    if (arr.length === 0) return 0;
    
    let sum = 0;
    for (let i = 0; i < arr.length; i++) {
        sum += arr[i];
    }
    return sum / arr.length;
}

let numbers = [10, 20, 30, 40, 50];
console.log("Array:", numbers);
console.log("Average:", averageLoop(numbers));

// Method 2: Using reduce
function averageReduce(arr) {
    if (arr.length === 0) return 0;
    
    let sum = arr.reduce((acc, num) => acc + num, 0);
    return sum / arr.length;
}

console.log("\nUsing reduce:", averageReduce([5, 10, 15, 20]));

// Method 3: Using forEach
function averageForEach(arr) {
    if (arr.length === 0) return 0;
    
    let sum = 0;
    arr.forEach(num => sum += num);
    return sum / arr.length;
}

console.log("\nUsing forEach:", averageForEach([2, 4, 6, 8, 10]));

// Method 4: One-liner with reduce
const average = arr => arr.length ? arr.reduce((a, b) => a + b) / arr.length : 0;

console.log("\nOne-liner:", average([1, 2, 3, 4, 5]));

// Method 5: With precision
function averagePrecise(arr, decimals = 2) {
    if (arr.length === 0) return 0;
    let avg = arr.reduce((a, b) => a + b) / arr.length;
    return parseFloat(avg.toFixed(decimals));
}

console.log("\nWith precision:", averagePrecise([1, 2, 3], 2));

Output

Array: [ 10, 20, 30, 40, 50 ]
Average: 30

Using reduce: 12.5

Using forEach: 6

One-liner: 3

With precision: 2

Understanding Array Average

This program demonstrates different methods to calculate the average of array elements.

Average Formula

Average = Sum of all elements / Number of elements

Method 1: For Loop

Traditional iterative approach:

let sum = 0;
for (let i = 0; i < arr.length; i++) {
    sum += arr[i];
}

return sum / arr.length;

Method 2: Reduce

Functional approach:

let sum = arr.reduce((acc, num) => acc + num, 0);

return sum / arr.length;

Reduce Syntax:

arr.reduce((accumulator, currentValue) => {
}, initialValue);

    // return new accumulator

Method 3: ForEach

Iterate and accumulate:

let sum = 0;
arr.forEach(num => sum += num);

return sum / arr.length;

ForEach vs For Loop:

•ForEach: Functional, can't break

•For loop: Can break/continue, more control

Method 4: Arrow Function One-Liner

Concise ES6 syntax:

const average = arr => arr.length ? arr.reduce((a, b) => a + b) / arr.length : 0;

Ternary Operator:

•Checks if array has elements

•Returns 0 if empty (avoid division by zero)

Method 5: With Precision

Control decimal places:

return parseFloat(avg.toFixed(decimals));

Number Methods:

•toFixed(n): Rounds to n decimals, returns string

•parseFloat(): Converts string to number

Edge Cases:

•Empty array: Return 0 or handle error

•Single element: Returns that element

•Negative numbers: Works normally

When to Use:

Loop

: Learning, simple

Reduce

: Modern, functional

One-liner

: Quick calculations

Precise

: When decimal control needed

Let us now understand every line and the components of the above program.

Note: To write and run JavaScript programs, you need to set up the local environment on your computer. Refer to the complete article Setting up JavaScript Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your JavaScript programs.

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