How to do reduce math.max to an array of objects

Question

I have an array of objects. I want to get the max out of the number attribute from the array:

[
  {number: 1000, name: "Josh"}, 
  {number: 2000, name: "Joker"}, 
  {number: 3000, name: "Batman"}
]

I'm using this solution but I keep getting NAN:

const max = arr.reduce((a, b) => Math.max(a.number, b.number));

My goal is to get the max and then store it in a variable

const x = { number: 3000, name: "Batman"}

How would I achieve it with reduce? It seems like it is only working with array of numbers.

Answer 1

Done by simple reduce,

var arr=[{"number":1000,"name":"Josh"},{"number":2000,"name":"Joker"},{"number":3000,"name":"Batman"}]
   
var x = arr.reduce((acc, i)=>(i.number > acc.number ? i : acc))

console.log(x)

Answer 2

With Array.prototype.reduce, you have to remember that the first argument passed to the callback is the accumulator. That is, the return value from the previous iteration.

Math.max returns a Number (or NaN if the operands cannot be compared numerically) so on the second iteration, you will be trying to compare the number property of a Number which won't work.

As an alternative to reduce, you might want to consider sorting the array. This could be beneficial if you want other properties like the smallest value.

// smallest to largest, use "b.number - a.number" to reverse
arr.sort((a, b) => a.number - b.number) 
arr[0] // smallest
arr[arr.length - 1] // largest