Bresenham's Line Algorithm - Produces a list of points from start to end

get_line.js

function get_line(start, end) {
  let [x1, y1] = start;
  let [x2, y2] = end;

  let dx = x2 - x1;
  let dy = y2 - y1;

  const is_steep = Math.abs(dy) > Math.abs(dx);

  // Rotate line
  if (is_steep) {
    [x1, y1] = [y1, x1];
    [x2, y2] = [y2, x2];
  }

  // Swap start and end points if necessary and store swap state
  let swapped = false;

  if (x1 > x2) {
    [x1, x2] = [x2, x1];
    [y1, y2] = [y2, y1];
    swapped = true;
  }

  // Recalculate differences
  dx = x2 - x1;
  dy = y2 - y1;

  let error = Math.floor(dx / 2.0);
  let ystep = -1;
  if (y1 < y2) {
    ystep = 1;
  }

  // Iterate over bounding box generating points between start and end
  let y = y1;
  const points = [];

  for (let i = x1; i <= x2; i++) {
    let coord = [y, i];
    if (!is_steep) {
      coord = [i, y];
    }

    points.push(coord);

    error -= Math.abs(dy);

    if (error < 0) {
      y += ystep;
      error += dx;
    }
  }

  if (swapped) {
    points.reverse();
  }

  return points;
}

let points = get_line([0, 0], [3, 4]);
console.log(points);