Finding the greatest and smallest number in a space separated string of numbers using JavaScript

We are required to write a JavaScript function that takes in a string containing numbers separated by spaces and returns a string with only the greatest and smallest numbers separated by a space.

Problem Statement

Given a space-separated string of numbers, find the maximum and minimum values and return them as a formatted string.

Input:

'5 57 23 23 7 2 78 6'

Expected Output:

'78 2'

Because 78 is the greatest and 2 is the smallest number in the string.

Using Array.reduce() Method

The most efficient approach uses reduce() to iterate through the array once and track both maximum and minimum values:

const str = '5 57 23 23 7 2 78 6';

const pickGreatestAndSmallest = (str = '') => {
    const strArr = str.split(' ');
    let creds = strArr.reduce((acc, val) => {
        let { greatest, smallest } = acc;
        greatest = Math.max(val, greatest);
        smallest = Math.min(val, smallest);
        return { greatest, smallest };
    }, {
        greatest: -Infinity,
        smallest: Infinity
    });
    return `${creds.greatest} ${creds.smallest}`;
};

console.log(pickGreatestAndSmallest(str));

78 2

Using Math.max() and Math.min() with Spread Operator

A more concise approach uses the spread operator with Math.max() and Math.min():

const str = '5 57 23 23 7 2 78 6';

const findMinMax = (str) => {
    const numbers = str.split(' ').map(Number);
    const max = Math.max(...numbers);
    const min = Math.min(...numbers);
    return `${max} ${min}`;
};

console.log(findMinMax(str));

78 2

Using Simple Loop Approach

For better readability, you can use a simple for loop:

const str = '5 57 23 23 7 2 78 6';

const findGreatestSmallest = (str) => {
    const numbers = str.split(' ').map(Number);
    let max = numbers[0];
    let min = numbers[0];
    
    for (let i = 1; i < numbers.length; i++) {
        if (numbers[i] > max) max = numbers[i];
        if (numbers[i] < min) min = numbers[i];
    }
    
    return `${max} ${min}`;
};

console.log(findGreatestSmallest(str));

78 2

Comparison of Methods

Key Points

• Always convert string values to numbers using Number() or map(Number)
• The spread operator approach is most concise for small arrays
• For large datasets, the loop approach offers better performance
• Handle edge cases like empty strings or invalid input

Conclusion

The spread operator with Math.max() and Math.min() provides the cleanest solution for finding greatest and smallest numbers in a space-separated string. Choose the approach based on your performance requirements and code readability preferences.