JavaScript - Node function - isValidPath: Checks a two-dimensional array ex: [[x1,y1],[x2,y2]] for validity against a collision map.

isValidPath.js

 // TODO - Grid axis is not being checked properly.
  isValidPath: function (grid, path) {
    // Check collision from an axis, n1 to n2, n3 is for the other axis.
    var c1to2on3 = function (n1,n2,n3,axis) {
      log.info("c1to2on3 - n1:"+n1+",n2:"+n2+",n3:"+n3);
      var isDec = (n3 % 1 == 0);
      var n1f = Math.floor(n1), n2c = Math.ceil(n2);
      var i1 = Math.min(n1f,n2c), i2 = Math.max(n1f,n2c);
      if (n1f != n2c) {
        var n3f=Math.floor(n3), n3c=Math.ceil(n3);
        if (axis == "x") {
          for (var i=i1; i < i2; i++) {
            if (isDec) {
              if (grid[n3][i]) {
                return false;
              }
            }
            else {
              if (grid[n3f][i] || grid[n3c][i]) {
                return false;
              }
            }
          }
        } else {
          for (var i=i1; i < i2; i++) {
            if (isDec) {
              if (grid[i][n3]) {
                return false;
              }
            }
            else {
              if (grid[i][n3f] || grid[i][n3c]) {
                return false;
              }
            }
          }
        }
      }
      return true;
    }

    var xf = function (x1,x2,y) {
      return c1to2on3(x1,x2,y,"x");
    }
    var yf = function (y1,y2,x) {
      return c1to2on3(y1,y2,x,"y");
    }

    var path2 = [];
    for (var i = 0; i < path.length; i++)
        path2[i] = path[i].slice();

    var pCoord;
    var ts = G_TILESIZE;
    for (var coord of path2) {
      coord[0] /= ts;
      coord[1] /= ts;
    }
    for (var coord of path2) {
      if (!pCoord) pCoord = coord;
      if (pCoord) {
        if (Math.abs(coord[0] - pCoord[0]) > 0) {
          if (!xf(pCoord[0], coord[0], coord[1]))
            return false;
        }
        if (Math.abs(coord[1] - pCoord[1]) > 0) {
          if (!yf(pCoord[1], coord[1], coord[0]))
            return false;
        }
      }
    }
    return true;
  },