how to use reduce to add valus inside array code example

Example 1: javascript sum of array

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

Example 2: add all elements in array javascript

console.log(
  [1, 2, 3, 4].reduce((a, b) => a + b, 0)
)
console.log(
  [].reduce((a, b) => a + b, 0)
)