js array elements sum

1const arr = [1, 2, 3, 4];
2const sum = arr.reduce((a, b) => a + b, 0);
3// sum = 10

1[1, 2, 3, 4].reduce((a, b) => a + b, 0)
2
3// Output: 10

1const sum = arr => arr.reduce((a, b) => a + b, 0);

1arrSum = function(arr){  return arr.reduce(function(a,b){    return a + b  }, 0);}

1let sum = (...para) => para.reduce((d,b) => d + b);

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