javascript reduce 28 29

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

1 let sum = arr.reduce((curr, index) => curr + index);

1let newArray = array.reduce( (acc, element, index, originalArray) => {
2    // return acc += element
3}, initialValue)

1function reduce(array, func, seed) {
2  let previousResult;
3  if (seed === undefined) {
4    previousResult = array[0];
5    for (let i = 1; i < array.length; i++) {
6      previousResult = func(previousResult, array[i], i, array);
7    }
8    console.log(previousResult);
9  } else {
10    previousResult = seed;
11    each(array, function(e, i, a) {
12      previousResult = func(previousResult, e, i, array);
13    });
14  }
15  return previousResult;
16};

1const developers = [
2  {
3    name: "Eliza",
4    experience: 7,
5    role: "manager"
6  },
7  {
8    name: "Manuel",
9    experience: 2,
10    role: "developer"
11  },
12  {
13    name: "Kim",
14    experience: 5,
15    role: "developer"
16  }
17];
18
19function calculateAverage(total, years, index, array) {
20  total += years;
21  return index === array.length-1 ? total/array.length: total
22}
23
24const average = developers.map(dev => dev.experience).reduce(calculateAverage);