how to find the index of the maximum value in an array javascr code example

Example 1: how to find index of max number in js

var a = [0, 21, 22, 7];
var indexOfMaxValue = a.reduce((iMax, x, i, arr) => x > arr[iMax] ? i : iMax, 0);

document.write("indexOfMaxValue = " + indexOfMaxValue); // prints "indexOfMaxValue = 2"

Example 2: Find the maximum number of an array js

Math.max(10, 20);   //  20
Math.max(-10, -20); // -10
Math.max(-10, 20);  //  20