1let flattened = [[0, 1], [2, 3], [4, 5]].reduce(
2  function(accumulator, currentValue) {
3    return accumulator.concat(currentValue)
4  },
5  []
6)
7// flattened is [0, 1, 2, 3, 4, 5]
8

1const sum = arr => arr.reduce((a, b) => a + b, 0);

1var array = [36, 25, 6, 15];
2
3array.reduce(function(accumulator, currentValue) {
4  return accumulator + currentValue;
5}, 0); // 36 + 25 + 6 + 15 = 82

1const numbers = [15.5, 2.3, 1.1, 4.7];
2document.getElementById("demo").innerHTML = numbers.reduce(getSum, 0);
3
4function getSum(total, num) {
5  return total + Math.round(num);
6}

1const sum = array.reduce((accumulator, element) => {
2  return accumulator + element;
3}, 0);
4// An example that will loop through an array adding
5// each element to an accumulator and returning it
6// The 0 at the end initializes accumulator to start at 0
7// If array is [2, 4, 6], the returned value in sum
8// will be 12 (0 + 2 + 4 + 6)
9
10const product = array.reduce((accumulator, element) => {
11  return accumulator * element;
12}, 1);
13// Multiply all elements in array and return the total
14// Initialize accumulator to start at 1
15// If array is [2, 4, 6], the returned value in product
16// will be 48 (1 * 2 * 4 * 6)

1
2  var numbers = [175, 50, 25];
3
4document.getElementById("demo").innerHTML 
5  = numbers.reduce(myFunc);
6
7function myFunc(total, num) {
8  
9  return total - num;
10}