Iterate an array as a pair (current, next) in JavaScript

Question

In the question Iterate a list as pair (current, next) in Python, the OP is interested in iterating a Python list as a series of current, next pairs. I have th

Answer 1

Here's a simple one-liner:

[1,2,3,4].reduce((acc, v, i, a) => { if (i < a.length - 1) { acc.push([a[i], a[i+1]]) } return acc; }, []).forEach(pair => console.log(pair[0], pair[1]))

Or formatted:

[1, 2, 3, 4].
reduce((acc, v, i, a) => {
  if (i < a.length - 1) {
    acc.push([a[i], a[i + 1]]);
  }
  return acc;
}, []).
forEach(pair => console.log(pair[0], pair[1]));

which logs:

1 2
2 3
3 4