JavaScript - get index of greatest value in array

In this article, we would like to show you how to get the index of the greatest value in an array in JavaScript.

Quick solution:

// ONLINE-RUNNER:browser;

var numbers = [2, 3, 1]

var indexOfMax = numbers.indexOf(Math.max(...numbers));

console.log(indexOfMax);  // 1

Note:

This solution is not optimal.

Practical example

In this example, we present a reusable function that also works in older web browsers.

// ONLINE-RUNNER:browser;

function indexOfMax(array) {
    if (array.length === 0) {
        return -1;
    }

    var max = array[0];
    var result = 0;

    for (var i = 1; i < array.length; ++i) {
        if (array[i] > max) {
            result = i;
            max = array[i];
        }
    }

    return result;
}


// Usage example:

var numbers = [2, 3, 1];

var maxIndex = indexOfMax(numbers);

console.log(maxIndex); // 1

See also

1. JavaScript - max value in array

2. JavaScript - Math.max() method example

References

1. Array.prototype.indexOf() - JavaScript | MDN
2. Math.max() - JavaScript | MDN
3. Spread syntax (...) - JavaScript | MDN