const array  = [5,4,7,8,9,2]; 

// Sum in array javascript
array.reduce((a,b) => a+b);
array.reduce((total, item) => total + item);
// Output: 35

// MAX in array javascript
array.reduce((a,b) => a>b?a:b);
// For max, this is way faster:
Math.max(...array);
// Output: 9

// MIN in array javascript
array.reduce((a,b) => a<b?a:b);
// For min this is way faster
Math.min(...array);
// Output: 2