Finding the key of the max value in a javascript array

Question

I have an empty array into which I am pushing values using javascript. I am able to find the max value of the array and set that to a variable using the following:

Array.max = function( array ){
 return Math.max.apply( Math, array );
};
var maxX = Array.max(xArray);

How can I find the key associated with that value?

• ZER0: You mean, the index? And what should be the logic if multiple indexes have the maximum value? (e.g. [1, 4, 2, 4])

Answer 1

Assuming that the values are unique, you could use Array.indexOf:

var maxX = Array.max(xArray);
var index = xArray.indexOf(maxX);

If the keys are not unique, index will contain the key of the first element found. If the value does not exist at all, the "key" will be -1.

• human: Array.max() is not even an existing function, I believe you meant Math.max.apply()
• Joey Gough: for me I had to spread my array inside Math.max like Math.max(...[1, 2, 3])