the use of reducers reactjs code example

Example 1: how to use reduce in javascript

const sum = array.reduce((accumulator, element) => {
  return accumulator + element;
}, 0);
// An example that will loop through an array adding
// each element to an accumulator and returning it
// The 0 at the end initializes accumulator to start at 0
// If array is [2, 4, 6], the returned value in sum
// will be 12 (0 + 2 + 4 + 6)

const product = array.reduce((accumulator, element) => {
  return accumulator * element;
}, 1);
// Multiply all elements in array and return the total
// Initialize accumulator to start at 1
// If array is [2, 4, 6], the returned value in product
// will be 48 (1 * 2 * 4 * 6)

Example 2: react/redux reducers sintaxe

const reduxSinaxe = (state = [], action) => {
  switch (action.type) {
    case "@smthg/ACTION":
      const { anyConst } = action;
      return [...state, anyConst];

    default:
      return state;
  }
};

export default reduxSinaxe;