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javascriptarraysmax

Return index of greatest value in an array

I have this:

var arr = [0, 21, 22, 7];

What's the best way to return the index of the highest value into another variable?

Solution

  • This is probably the best way, since it’s reliable and works on old browsers:

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

    var max = arr[0];
    var maxIndex = 0;

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

    return maxIndex;
}

    There’s also this one-liner:

    let i = arr.indexOf(Math.max(...arr));

    It performs twice as many comparisons as necessary and will throw a RangeError on large arrays, though. I’d stick to the function.