Returning an array with the minimum and maximum elements JavaScript

Finding the minimum and maximum elements in a JavaScript array is a common task. This tutorial shows how to return both values in a single array using different approaches.

const arr = [12, 54, 6, 23, 87, 4, 545, 7, 65, 18, 87, 8, 76];

We need to write a function that finds the minimum and maximum elements and returns them as an array with minimum at index 0 and maximum at index 1.

Using Array.reduce() Method

The reduce() method provides an efficient way to traverse the array once and track both minimum and maximum values:

const arr = [12, 54, 6, 23, 87, 4, 545, 7, 65, 18, 87, 8, 76];

const minMax = (arr) => {
    return arr.reduce((acc, val) => {
        if(val < acc[0]){
            acc[0] = val;
        }
        if(val > acc[1]){
            acc[1] = val;
        }
        return acc;
    }, [Infinity, -Infinity]);
};

console.log(minMax(arr));

[ 4, 545 ]

Using Math.min() and Math.max()

A simpler approach uses the built-in Math.min() and Math.max() methods with the spread operator:

const arr = [12, 54, 6, 23, 87, 4, 545, 7, 65, 18, 87, 8, 76];

const minMaxSimple = (arr) => {
    return [Math.min(...arr), Math.max(...arr)];
};

console.log(minMaxSimple(arr));

[ 4, 545 ]

Using a For Loop

For better performance with very large arrays, a traditional for loop works efficiently:

const arr = [12, 54, 6, 23, 87, 4, 545, 7, 65, 18, 87, 8, 76];

const minMaxLoop = (arr) => {
    let min = arr[0];
    let max = arr[0];
    
    for(let i = 1; i < arr.length; i++) {
        if(arr[i] < min) min = arr[i];
        if(arr[i] > max) max = arr[i];
    }
    
    return [min, max];
};

console.log(minMaxLoop(arr));

[ 4, 545 ]

Comparison

Handling Edge Cases

Always check for empty arrays to avoid errors:

const minMaxSafe = (arr) => {
    if(arr.length === 0) return [undefined, undefined];
    return [Math.min(...arr), Math.max(...arr)];
};

console.log(minMaxSafe([]));
console.log(minMaxSafe([42]));

[ undefined, undefined ]
[ 42, 42 ]

Conclusion

Use Math.min()/Math.max() for simplicity and readability. For large arrays, prefer the for loop approach for better performance. Always handle empty arrays to prevent runtime errors.