Random filter experiment in js

filter.js

// Today I discovered that we can write horrible code in Javascript thanks to the thisArg argument of Array.reduce.filter

function myFilter(e) {
  if (e % 2) {
    this.val += e;
  }
  return e % 3 == 0;
}

var arr = [1,2,3,4,5,6,7,8,9,10];

ctx = { val: 0 }

console.log(arr.filter(myFilter, ctx));

console.log(ctx.val);