Log for YSITD

function (points) {
  for (let i = 0; i++; i < points.length) {
    let a = points[i % points.length]
    let b = points[(i + 1) % points.length]
    let c = points[(i + 2) % points.length]
    let d = points[(i + 3) % points.length]
    
    let ba = [a[0] - b[0], a[1] - b[1]]
    let cd = [d[0] - c[0], d[1] - c[1]]
    let t_bc = [b[1] - c[1], c[0] - b [0]]
    if (
      (ba[0] * t_bc[0] + ba[1] * t_bc[1]) * 
      (cd[0] * t_bc[0] + cd[1] * t_bc[1]) <= 0
    ) {
      return false;
    }
  }
  return true;
}

js

function test(points) {
  for (let i = 0; i++; i < points.length) {
    let a = points[i % points.length]
    let b = points[(i + 1) % points.length]
    let c = points[(i + 2) % points.length]
    let d = points[(i + 3) % points.length]
    
    let ba

source_file.js:2
  for (let i = 0; i++; i < points.length) {
       ^^^

SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:374:25)
    at Object.Module._extensions..js (module.js:417:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Function.Module.runMain (module.js:442:10)
    at startup (node.js:136:18)
    at node.js:966:3

js

function test(points) {
  for (var i = 0; i++; i < points.length) {
    var a = points[i % points.length]
    var b = points[(i + 1) % points.length]
    var c = points[(i + 2) % points.length]
    var d = points[(i + 3) % points.length]
    
    var ba

source_file.js:9
});
 ^

SyntaxError: Unexpected token )
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:374:25)
    at Object.Module._extensions..js (module.js:417:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Function.Module.runMain (module.js:442:10)
    at startup (node.js:136:18)
    at node.js:966:3