How to use reduce with React?

What is the use of reduce in Javascript?

The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in single output value.

let a=[1,5,6,7,8];
let total=a.reduce((total,currentValue)=>total+currentValue)
console.log(total);//prints 27

In the above example, we are using reduce for sum of array.

What in case if you want to pass a value to accumulator?

reduce accepts two params function, param.

let a=[1,5,6,7,8];
let total=a.reduce(((total,currentValue)=>total+currentValue),20)
console.log(total);//prints 47

How to use reduce in react now?

import React, { Component } from 'react'

export default class App extends Component {
  render() {
    let a=[1,5,6,7,8];
    let total=a.reduce(((total,currentValue)=>total+currentValue),20)

    return (
      <div>
        Total sum is {total}    
      </div>
    )
  }
}