[removed] Using reduce() to find min and max values?

Question

I have this code for a class where I\'m supposed to use the reduce() method to find the min and max values in an array. However, we are required to use only a single call to

Answer 1

As the reduce call isn't really needed at all, you could have some fun with it

let items = [62, 3, 7, 9, 33, 6, 322, 67, 853];

let arr = items.reduce((w,o,r,k,s=Math)=>[s.min.apply(0, k),s.max.apply(0, k)],[]);

console.log(arr);

All you'd really need is let minMaxArray = [Math.min.apply(0,items), Math.max.apply(0,items)]

Answer 2

const values = [1,2,3,4,5];
const [first] = values;
const maxValue = values.reduce((acc, value) => Math.max(acc, value), first);

Answer 3

1. Solution using only Math.min and Math.max:

⚠️ This will not work if you use big arrays, i.e. supply Math.min() with many arguments as "you run the risk of exceeding the JavaScript engine's argument length limit. The consequences of applying a function with too many arguments (think more than tens of thousands of arguments) vary across engines (JavaScriptCore has hard-coded argument limit of 65536), because the limit (indeed even the nature of any excessively-large-stack behavior) is unspecified. Some engines will throw an exception." from MDN web docs.

function minMax(items) {
  return [
      Math.min.apply(null, items),
      Math.max.apply(null, items)
  ]
}

... or if you prefer ES6's Spread syntax:

const minMax = items => [
  Math.min(...items),
  Math.max(...items)
]

2. Solution using Array.prototype.reduce, Math.min and Math.max

function minMax(arr) {
  return arr.reduce(function(acc, cur) {
    return [
      Math.min(cur, acc[0]),
      Math.max(cur, acc[1])
    ]
  }, [Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY]);
}

... or shortened:

const minMax = items =>
  items.reduce((acc, cur) =>
    [Math.min(cur, acc[0]), Math.max(cur, acc[1])],
    [Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY]
  )

3. Solution including sensible validations

function minMax(items) {
  let newItems = []
  const isArray = Array.isArray(items)
  const onlyHasNumbers = !items.some(i => isNaN(parseFloat(i)))

  // only proceed if items is a non-empty array of numbers
  if (isArray && items.length > 0 && onlyHasNumbers) {
    newItems = items.reduce(function(acc, cur) {
      return [
        Math.min(cur, acc[0]),
        Math.max(cur, acc[1])
      ]
    }, [Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY])
  }
  return newItems
}

Documentation for Math.min

Documentation for Math.max

Documentation for Array.prototype.reduce()

Answer 4

You can use do like this. There can be any number of arguments.

function minValue(...args) {
    const min = args.reduce((acc, val) => {
        return acc < val ? acc : val;
    });
    return min;
}

function maxValue(...args) {
    const max= args.reduce((acc, val) => {
        return acc > val ? acc : val;
    });
    return max;
}

Answer 5

To get min and max value of an array using reduce function

const ArrayList = [1, 2, 3, 4, 3, 20, 0];
const LargestNum = ArrayList.reduce((prev, curr) => {
      return Math.max(prev, curr)
});
const MinNum = ArrayList.reduce((prev,curr)=>{
      return Math.min(prev,curr)
});
console.log(LargestNum);
console.log(MinNum);