sum of all numbers in an array javascript

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

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

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

arr.reduce((a, b) => a + b)

arrSum = function(arr){  return arr.reduce(function(a,b){    return a + b  }, 0);}

array.reduce((a, b) => a + b, 0)