Output a table of array of arrays in the console.

to-table.js

function toTable(data, headings=[], cellspacing=2, cellpadding=1) {
  const widths = data.concat([headings]).reduce((widths, r) => r.reduce((ws, c, i) => {
    let cur = ws[i] || 0, w = String(c).length;
    ws[i] = w > cur ? w : cur;
    return ws;
  }, widths), []).map(w => w + cellpadding * 2), cs = center('|', cellspacing + 1);

  if(headings.length) {
    console.log(headings.map((h, i) => pad(center(h, widths[i]))).join(cs));
    console.log(widths.map(w => '-'.repeat(w+cellpadding*2)).join(cs));
  }
  data.forEach(r => console.log(r.map((c, i) => pad(align(c, widths[i]))).join(cs)));

  function align(val, w) {
    const p = ' '.repeat(w - String(val).length);
    return typeof val === 'number' ? p + val : val + p;
  }
  function center(val, w) {
    const half = (w - String(val).length) / 2;
    return ' '.repeat(Math.ceil(half)) + val + ' '.repeat(Math.floor(half));
  }
  function pad(cell) {
    const padding = ' '.repeat(cellpadding);
    return padding+cell+padding;
  }
}