How to find the closest value to zero from an array with positive and negative numbers in JavaScript

Learn how to find the closest value to zero from a collection of numbers inside an array in JavaScript.

On the last days, I needed to fill a codingame test that exposed the following problem that needed to be solved:

In this exercise, you have to analyze records of temperature to find the closest to zero. Sample temperatures. Here, -1.7 is the closest to 0. Implement the function closestToZero to return the temperature closer to zero which belongs to the array ts.

If ts is empty, return 0 (zero).
If two numbers are as close to zero, consider the positive number as the closest to zero (eg. if ts contains -5 and 5, return 5).

Input:

Temperatures are always expressed with floating-point numbers ranging from -273 to 5526.
ts is always a valid array and is never null.

Solution

Based on the exposed data, the following implementation solves the problem:

/**
 * From a collection of numbers inside an array, returns the closest value to zero.
 */
function closestToZero(numbers) {
    if(!numbers.length){
        return 0;
    }
    
    let closest = 0;
    
    for (let i = 0; i < numbers.length ; i++) {
        if (closest === 0) {
            closest = numbers[i];
        } else if (numbers[i] > 0 && numbers[i] <= Math.abs(closest)) {
            closest = numbers[i];
        } else if (numbers[i] < 0 && - numbers[i] < Math.abs(closest)) {
            closest = numbers[i];
        }
    }
    
    return closest;
}

You can test the code with different examples of your own:

let items = [7,-10, 13, 8, 4, -7.2,-12,-3.7,3.5,-9.6, 6.5,-1.7, -6.2,7];
// Result: -1.7
console.log("Result: " + closestToZero(items));

items = [5, 6, 7, 9 , 2, - 2];
// Result: 2
console.log("Result: " + closestToZero(items));

items = [];
// Result: 0
console.log("Result: " + closestToZero(items));

Alternatively, one of the solutions of the community includes as well this other option:

function closestToZero(numbers)
{
    if (numbers.length === 0) return 0;
    
    let closest = numbers[0];

    for(let i = 0; i < numbers.length;i++){
        let number = numbers[i];
        let absNumber =  Math.abs(number);
        let absClosest = Math.abs(closest);

        if (absNumber < absClosest) 
        {
            closest = number;
        } 
        else if (absNumber === absClosest && closest < 0) 
        {
            closest = number;
        }
    }

    return closest;
}

Happy coding ❤️!