Javascript method reduce()

• JavaScript Array reduce() Method, w3schools
• Simplify your JavaScript – Use .map(), .reduce(), and .filter(), Etienne Talbot
• Write JavaScript loops using map, filter, reduce and find, Flavop Copes
• JavaScript’s Reduce Method Explained By Going On a Diet
• One reduce() to rule them all — How to use reduce in JavaScript, Kristian Poslek
• Javascript `reduce` 101, Igor Irianto

It took some reading before I started understanding the Javascript method reduce ().

According to w3schools:

• The reduce() method reduces the array to a single value.
• The reduce() method executes a provided function for each value of the array (from left-to-right).
• The return value of the function is stored in an accumulator (result/total).

A simple example of the method reduce():

function testOne(){

var serviceFee = 1000;
var invoice = [serviceFee,21*serviceFee/100];

  var result = invoice.reduce(function(accumulator,currentValue){
    return accumulator + currentValue;
  },0)
//1210.0
}

The single value to which an array is reduced can also be a text.

function testTwo(){

var nameArray = ["Mariette","Timmer"];

  var result =  nameArray.reduce(function(accumulator,currentValue){
    return accumulator + currentValue;
  })
//MarietteTimmer
}

The single value to which an array is reduced can even be an array (updated 12-01-2020 13:17).

function testThree(){

var arrayOne = ["Aap","Noot","Mies","Wim","Zus","Jet"];

  var result =  arrayOne.reduce(function(accumulator,currentValue){
    if(currentValue.length > 3){
      accumulator.push(currentValue);
    }
    return accumulator;
  },[])
//[Noot, Mies]
}

My own imagination seems to be the limit.