Answers for "javascript array reduce"

javascript reduce

/* reduce method: combine an array's values together, left to right */

let myArray = [1, 2, 3];

let a = myArray.reduce((initial, current) => initial + current, 0);
// [0 + 1 + 2 + 3] → 6

let b = myArray.reduce((initial, current) => initial + (current*10), 7);
// [7 + (1*10) + (2*10) + (3*10)] → 67

// Combine right to left with .reduceRight
let c = myArray.reduceRight((initial, current) => initial / current, 30);
// [30 / 3 / 2 / 1] → 5

/* Syntax: array.reduce((accumulator, currentValue) =>
combineFunction, accumulatorStartValue); */

javascript reduce

You can return whatever you want from reduce method, reduce array method good for computational problems
const arr = [36, 25, 6, 15];
array.reduce(function(accumulator, currentValue) {
  return accumulator + currentValue;
}, 0); // this will return Number
array.reduce(function(accumulator, currentValue) {
  return accumulator + currentValue;
}, []); // this will return array
let {total} = array.reduce(function(accumulator, currentValue) {
  let {currentVal} = currentValue
  return accumulator + currentVal;
}, {
total: 0
}); // this will return object
And one additional rule is always always retrun the first param, which do arithmetic operations.